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sx07CAGr8_VPhyLab_FM.fm Page i Thursday, July 19, 2007 8:35 AM Virtual Physical Science Lab Record Sheets Brian F. Woodfield Heather J. McKnight Steven Haderlie Bradley D. Moser Boston, Massachusetts Upper Saddle River, New Jersey sx07CAGr8_VPhyLab_FM.fm Page ii Thursday, July 19, 2007 8:35 AM Copyright © by Pearson Education, Inc., publishing as Pearson Prentice Hall, Boston, Massachusetts 02116. All rights reserved. Printed in the United States of America. This publication is protected by copyright, and permission should be obtained from the publisher prior to any prohibited reproduction, storage in a retrieval system, or transmission in any form or by any means, electronic, mechanical, photocopying, recording, or likewise. The publisher hereby grants permission to reproduce the student worksheets, in part or in whole, for classroom use only, the number not to exceed the number of students in each class. Notice of copyright must appear on all copies. For information regarding permission(s), write to: Rights and Permissions Department, One Lake Street, Upper Saddle River, New Jersey 07458. Pearson Prentice Hall™ is a trademark of Pearson Education, Inc. Pearson® is a registered trademark of Pearson plc. Prentice Hall® is a registered trademark of Pearson Education, Inc. 13-digit ISBN 978-0-13-362834-0 10-digit ISBN 0-13-362834-5 1 2 3 4 5 6 7 13 12 11 10 09 sx07CAGr8_VPhyLab_FM.fm Page iii Thursday, August 16, 2007 1:45 PM Contents Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v Installing Virtual Physical Science . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vii Getting Started. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xi Lab 1: Introduction to Scientific Inquiry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Lab 2: Making Sense of Density . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Lab 3: Investigation of Gas Pressure and Mass. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Lab 4: Pressure and Volume of a Gas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Lab 5: Pressure and Temperature of a Gas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Lab 6: Changes Between a Solid and a Liquid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Lab 7: Changes Between a Liquid and a Gas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Lab 8: Thomson and Smaller Parts of Atoms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Lab 9: Rutherford and the Nucleus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Lab 10: Elements and the Periodic Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 Lab 11: Density of Solids and Liquids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 Lab 12: Creating Chemical Compounds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 Lab 13: Names and Formulas of Ionic Compounds . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 Lab 14: Describing Chemical Reactions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 Lab 15: Using Energy to Observe Chemical Changes . . . . . . . . . . . . . . . . . . . . . . . . . . 39 Lab 16: Boiling Point Elevation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 © Pearson Education, Inc. All rights reserved. Lab 17: Endothermic vs. Exothermic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 Lab 18: Acid-Base Reactions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 Lab 19: Energy of a Chemical Reaction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 Lab 20: Investigating the Properties of Alpha and Beta Particles . . . . . . . . . . . . . . . . 52 Lab 21: Measuring Speed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 Lab 22: Graphing Motion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 Lab 23: Acceleration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60 Lab 24: Forces. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63 Lab 25: Measuring Friction: A Sticky Topic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 Lab 26: Acceleration and Friction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67 Contents iii sx07CAGr8_VPhyLab_FM.fm Page iv Wednesday, August 8, 2007 1:31 PM Lab 27: Gravity and Free Fall Motion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70 Lab 28: Newton’s First Law . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73 Lab 29: Newton’s Second Law . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76 Lab 30: Newton’s Third Law . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79 Lab 31: Conservation of Momentum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81 Lab 32: Floating Objects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84 Lab 33: Density and Buoyancy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87 Lab 34: The Work of the Egyptians. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91 Lab 35: Falling Elevator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95 Lab 36: Thermal Energy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98 Lab 37: Potential Energy to Kinetic Energy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101 Lab 38: Temperature and Volume of a Gas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104 Lab 39: Specific Heat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106 Lab 40: Blackbody Radiation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109 Lab 41: Wave Properties of Light . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112 Lab 42: Particle Properties of Light. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115 Lab 43: Atomic Emission of Spectra . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118 Lab 45: Concave Mirror Images . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122 Lab 46: Convex Mirror Images . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124 Lab 47: Looking at Images . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126 Lab 48: Ohm’s Law . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128 Lab 49: Circuit Diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130 Lab 50: Building Electrical Circuits. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133 Lab 51: Making Observations of Our Solar System . . . . . . . . . . . . . . . . . . . . . . . . . . . 137 Lab 52: Tracking the Phases of the Moon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139 Lab 53: Measuring the Orbital Speed of the Planets . . . . . . . . . . . . . . . . . . . . . . . . . . 143 Lab 54: How Strong is Gravity? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145 Lab 55: Why Pluto is Not a Planet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148 Answers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151 iv Contents © Pearson Education, Inc. All rights reserved. Lab 44: Plane Mirror Images . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120 sx07CAGr8_VPhyLab_FM.fm Page v Friday, August 10, 2007 12:27 PM © Pearson Education, Inc. All rights reserved. Overview Welcome to Virtual Physical Science, a set of realistic and sophisticated simulations covering topics in chemistry, physics, and planetary motion. In these laboratories, students are put into a virtual environment where they are free to make the choices and decisions that they would confront in an actual laboratory setting and, in turn, experience the resulting consequences. These laboratories include simulations of inorganic qualitative analysis, fundemental experiments in quantum chemistry, gas properties, titrations, calorimetry, mechanics and planetary motion, density, circuits, and optics. This overview and the installations instructions are for the single version of Virtual Physical Science v3.0. After installing the Virtual Physical Science simulations, the software is configured to access the laboratories either through the electronic workbook or by clicking on the Physical Science Laboratory door. The electronic workbook is designed to be used in conjunction with worksheets that are provided with the software and will most likely be the principle method for gaining access to the various laboratory simulations. However, students can also be given electronic assignments through the Web Connectivity Option that they accept inside the various laboratories and report their results back through the electronic lab book. These types of assignments are accessed by entering through the Virtual Physical Science door and providing a user name, password, and the URL address for the Y Science server. Details on receiving and submitting electronic assignments are given in the various laboratory user guides. It is strongly suggested the user guides be reviewed before running the software. See the Getting Started section for more information on using Virtual Physical Science with the accompanying workbook. A brief description of the nine chemistry and physics laboratories found in Virtual Physical Science is given below. The mechanics laboratory provides students the flexibility to perform many fundamental experiments to teach the basic concepts of Newton’s laws and planetary motion that are easier to model in a simulated situation rather than a real laboratory. The ability to control the frictions, forces, and physical parameters of motion allows students the ability to easily use equipment that can be found in most instructional laboratories and some equipment that would be less readily available. Students are able to measure speeds and distances, describe the motion of objects using graphs, interpret data, understand our solar system, and gain a foundation for concepts in physics. These results can then be used to validate Newton’s laws; demonstrate the interplay between force and motion; calculate conservation of momentum; and study the intricacies of the solar system under variable initial conditions and parameters. A partial list of the experiments performed in the mechanics laboratory include projectile motion in uniform or radial gravity, ramp motion in uniform or radial gravity, the collision of multiple balls with elastic or inelastic collisions, a falling rod, and the motion of the planets and their moons in the solar system viewed from various perspectives. The difficulty level of these experiments ranges from basic to sophisticated, depending on the level of the class and the purpose for performing the experiments. The features of the inorganic simulation include 26 cations that can be added to test tubes in any combination, 11 reagents that can be added to the test tubes in any sequence and any number of times, necessary laboratory manipulations, a lab book for recording results and observations, and a Overview v sx07CAGr8_VPhyLab_FM.fm Page vi Wednesday, August 8, 2007 1:31 PM vi Overview © Pearson Education, Inc. All rights reserved. stockroom for creating test tubes with known mixtures, generating practice unknowns, or retrieving instructor assigned unknowns. The simulation uses over 2,500 actual pictures to show the results of reactions and over 220 videos to show the different flame tests. With 26 cations that can be combined in any order or combination and 11 reagents that can be added in any order, there are in excess of 1016 possible outcomes for these simulations. The purpose of the quantum laboratory is to allow students to explore and better understand the foundational experiments that led to the development of atomic theory and an understanding of the atom. Because of the very sophisticated nature of most of these experiments, the quantum laboratory is the most “virtual” of the Virtual Physical Science laboratory simulations. In general, the laboratory consists of an optics table where a source, sample, modifier, and detector combination can be placed to perform different experiments. These devices are located in the stockroom and can be taken out of the stockroom and placed in various locations on the optics table. The emphasis here is to teach students to probe a sample (e.g., a gas, metal foil, twoslit screen, etc.) with a source (e.g., a laser, electron gun, alpha-particle source, etc.) and detect the outcome with a specific detector (e.g., a phosphor screen, spectrometer, etc.). Heat, electric fields, or magnetic fields can also be applied to modify an aspect of the experiment. As in all Virtual Physical Science laboratories, the focus is to allow students the ability to explore and discover, in a safe and level-appropriate setting, the concepts that are important in the various areas of chemistry. The gas experiments included in the Virtual Physical Science simulated laboratory allow students to explore and better understand the behavior of ideal gases, real gases, and van der Waals gases (a model real gas). The gases laboratory contains four experiments each of which includes the four variables used to describe a gas: pressure (P), temperature (T), volume (V), and the number of moles (n). The four experiments differ by allowing one of these variables to be the dependent variable while the others are independent. The four experiments include (1) V as a function of P, T, and n using a balloon to reflect the volume changes; (2) P as a function of V, T, and n using a motordriven piston; (3) T as a function of P, V, and n again using a motor-driven piston; and (4) V as a function of P, T, and n but this time using a frictionless, massless piston to reflect volume changes and using weights to apply pressure. The gases that can be used in these experiments include an ideal gas; a van der Waals gas with parameters that can be changed to represent any real gas; real gases including N2, CO2, CH4, H2O, NH3, and He; and eight ideal gases with different molecular weights that can be added to the experiments to form gas mixtures. The virtual titration laboratory allows students to perform precise, quantitative titrations involving acid-base and electrochemical reactions. The available laboratory equipment consists of a 50 mL buret, 5, 10, and 25 mL pipets, graduated cylinders, beakers, a stir plate, a set of 8 acid-base indicators, a pH meter/voltmeter, a conductivity meter, and an analytical balance for weighing out solids. Acid–base titrations can be performed on any combination of mono-, di-, and tri-protic acids and mono-, di-, and tri-basic bases. The pH of these titrations can be monitored using a pH meter, an indicator, and a conductivity meter as a function of volume, and this data can be saved to an electronic lab book for later analysis. A smaller set of © Pearson Education, Inc. All rights reserved. sx07CAGr8_VPhyLab_FM.fm Page vii Friday, August 10, 2007 12:35 PM potentiometric titrations can also be performed. Systematic and random errors in the mass and volume measurements have been included in the simulation by introducing buoyancy errors in the mass weighings, volumetric errors in the glassware, and characteristic systematic and random errors in the pH/ voltmeter and conductivity meter output. These errors can be ignored, which will produce results and errors typically found in high school or freshman-level laboratory work, or the buoyancy and volumetric errors can be measured and included in the calculations to produce results better than 0.1% in accuracy and reproducibility. The calorimetry laboratory provides students with three different calorimeters that allow them to measure various thermodynamic processes including heats of combustion, heats of solution, heats of reaction, the heat capacity, and the heat of fusion of ice. The calorimeters provided in the simulations are a classic “coffee cup” calorimeter, a dewar flask (a better version of a coffee cup), and a bomb calorimeter. The calorimetric method used in each calorimeter is based on measuring the temperature change associated with the different thermodynamic processes. Students can choose from a wide selection of organic materials to measure the heats of combustion; salts to measure the heats of solution; acids, bases, oxidants, and reductants for heats of reaction; metals and alloys for heat capacity measurements; and ice for a melting process. Temperature versus time data can be graphed during the measurements and saved to the electronic lab book for later analysis. Systematic and random errors in the mass and volume measurements have been included in the simulation by introducing buoyancy errors in the mass weighings, volumetric errors in the glassware, and characteristic systematic and random errors in the thermometer measurements. The density laboratory allows students the ability to measure the mass and volume of a large set of liquids and solids, which, in turn, will allow them to explore the fundamental concepts governing density and buoyancy. The laboratory has a set of graduated cylinders that can be filled with various liquids such as water, corn syrup, mercury, jet fuel, tar, plus many others. These cylinders can be filled with one or two liquids to study miscibility or the relative density of the liquids. The laboratory also contains a large selection of solids that can be dropped into these cylinders, and the students can then observe whether the solids float or sink in the selected liquids. The density of the solids can be calculated by measuring the mass of the solids and the volume of liquid displaced in the cylinders after the solids have been dropped into the liquid. The density of the liquids can be determined by measuring the mass and volume of the liquid. The circuit laboratory gives students the freedom to discover and learn the principles associated with simple electrical circuits involving resistors, capacitors, and inductors. The laboratory allows students to build circuits using either a breadboard or schematic representation. Using the breadboard students will connect components as they would in an ordinary circuit laboratory by adding resistors, light bulbs, capacitors, or inductors of any combination and a battery or function generator. When using the schematic the students can “draw” a circuit schematic on paper as they would to plan a circuit. The breadboard and schematic are linked together so they automatically populate when the other one is changed. Using the digital multimeter and oscilloscope this type is to justify para Installing Virtual Physical Science vii sx07CAGr8_VPhyLab_FM.fm Page viii Thursday, August 16, 2007 1:51 PM students can then analyze their circuits and learn principles like Ohm’s Law, the power-voltage relationship, AC/DC sources, and much more. The optics laboratory gives students the freedom to discover and learn the principles associated with simple optical experiments involving light sources, objects, mirrors, lenses, prisms, and filters. The laboratory allows students to set up optical experiments on a standard optics table by placing components on the table and moving the viewing detector or virtual eye to different locations to observe the resulting image characteristics. When setting up experiments with mirrors and lenses in different combinations, students can analyze their layouts to test image characteristics depending on object locations and verify the lensmaker equations. Principles of light addition and subtraction can be studied with filters and prism light recombination. Snell’s Law and the law of reflection can also be investigated. © Pearson Education, Inc. All rights reserved. viii Installing Virtual Physical Science sx07CAGr8_VPhyLab_FM.fm Page ix Thursday, August 16, 2007 1:51 PM System Requirements Minimum system requirements are as follows: PC Pentium 1 GHz (Pentium III or better recommended) 256 Mb RAM (512+ Mb Recommended) CD-ROM drive (for installation only) 1 Gb of free disk space Display capable of and set to millions of colors (24 bit color) Recommended minimum resolution 1024 x 768 Windows 2000 Professional or Windows XP QuickTime 6.x/7.x Macintosh PowerPC (G3 or better recommended) 256 Mb RAM (512+ Mb recommended) CD-ROM drive (for installation only) 1 Gb of free disk space Display capable of and set to millions of colors (24-bit color) Recommended minimum resolution 1024 x 768 OS X (any version) QuickTime 6.x/7.x Note: The above requirements are the recommended minimum hardware and system software requirements for reasonable execution speeds and reliability. However, it should be noted that the software has been successfully installed and used on computers with significantly lower capabilities than the recommendations given above with corresponding reductions in execution speed and media access time. Installing Virtual Physical Science © Pearson Education, Inc. All rights reserved. Locate and run the program “Setup VPS” on the CD-ROM drive then follow the prompts. There is only one install option available for the single user version, which installs the complete software package to the hard drive. The CD is not needed to run the program after performing the installation. Important Installation Notes and Issues 1. The graphics used in the simulations require the monitor to be set to 24-bit true color (millions of colors). Lower color resolutions can be used, but the graphics will not be as sharp. 2. When installing Virtual Physical Science, you must be logged in as an Administrative User in order for all files and folders to be installed correctly and to have correctly configured file permissions; otherwise, unpredictable results such as hard crashes and other errors can occur during installation and running Virtual Physical Science. 3. The Inorganic simulation will not run on some Macintosh Macbooks using an Intel-based processor. This is a known issue affecting all Adobe (formerly Macromedia) Director products, however there is some disagreement whether the fault is in Director or OS X. This problem does System Requirements ix sx07CAGr8_VPhyLab_FM.fm Page x Thursday, August 16, 2007 1:51 PM not appear on Macbook Pros and only on some regular Macbooks. The current solution to this issue is to install the software on Windows running in a virtual machine such as VMware or Parallels. 4. Occasionally when installing on the OS X operating system, the system fails to copy over the VCL icon for aliases created on the desktop. There is no known cause for this. Aliases with the correct icon can be created manually inside the installation directory or by copying a VCL icon on to an already existing alias. 5. When installing on the OS X operating system v10.4 (or Tiger), selecting the option to place an alias on the dock causes the dock to be reset to its initial installed state and any dock customization is lost. 6. In the directory where Virtual Physical Science is installed, the user must always have read/write privileges to that directory and all directories underneath. This is the default state for all Administrative Users (both Mac and PC), and this condition has been set by the installer for Standard Users in OS X as well. However, if users will be logged in as Restricted Users in Windows (such as in a computer lab), then the privileges for the Virtual Physical Science directory must be set manually to “Full Access” for Everyone. The installer attempts to set these permissions for Windows installations, but for unknown reasons it is not always successful. In addition, if the system crashes hard while running Virtual Physical Science (either on Windows or OS X), these permissions may have to be reset to read/write for everyone. 8. When installing Virtual Physical Science on to the OS X operating system, the user must have read/write permission for the folder into which Virtual Physical Science will be installed. In the vast majority of cases, Virtual Physical Science will be installed into the Applications folder, but in order for this to be successful the user must be an Administrative User. In some cases, however, the permissions for the Applications folder have been modified by other software installed on the machine, which will prevent Virtual Physical Science from being installed in the Applications folder. These permissions can be reset back to their default state using the Repair Disk Permissions function in the Disk Utility program located in the Applications folder. 9. QuickTime 6.0 or later is required for the software to run properly. The most recent version of QuickTime can be obtained at http://www.apple.com/quicktime/. 10. For unknown reasons, on some machines the QuickTime videos will not play properly if the system QuickTime settings are in their default state. This can be corrected by changing the Video Settings in QuickTime to Normal Mode. x Installing Virtual Physical Science © Pearson Education, Inc. All rights reserved. 7. The installer does not allow installation and other directory paths to be typed in directly, but all installation paths must be identified or selected by browsing to the desired location. When installing on the OS X operating system, browsing to a folder using aliases occasionally causes the installer to spontaneously shutdown. Consequently, it is recommend that aliases be avoided when browsing. There is no known cause for this. sx07CAGr8_VPhyLab_FM.fm Page xi Friday, August 17, 2007 6:54 AM Getting Started © Pearson Education, Inc. All rights reserved. After Virtual Physical Science has been successfully installed, the VPS icon used to launch the program will be located on the desktop, in a Program Group on PC machines, and on the Dock for Macintosh machines. Clicking on the VPS icon will start the simulation where you will be brought to a hallway containing two doors and a workbook sitting on a table (see Figure 1). Clicking on the electronic workbook opens and zooms into the workbook pages (see Figure 2) where you can select preset assignments that correspond to the assignments in the student workbook. The Previous and Next buttons are used to page through the set of assignments, and the different assignments can also be accessed by clicking on the section titles located on the left page of the workbook. Clicking on the Enter Laboratory button will allow you to enter the physical science laboratory (see below), and the Exit button is used to return to the hallway. From the hallway, students can also enter the physical science laboratory by clicking on the Physical Science Laboratory door and entering as a guest. Once in the laboratory, students will find nine laboratory benches that represent the nine different physical science laboratories. By mousing over each of these laboratory benches students can display the name of the selected laboratory. To access a specific laboratory, click on the appropriate laboratory bench. While in the physical science laboratory, the full functionality of the simulation is available, and students are free to explore and perform experiments as dictated by their instructors or by their own curiosity. The Exit signs in the physical science laboratory are used to return to the hallway. Detailed instructions on how to use each of the nine laboratory simulations can be found in the User Guides located in the Virtual Physical Science CD. These same user guides can also be accessed inside each laboratory by clicking on the Pull-Down TV and clicking on the Help button. For those students who will be given electronic assignments from their instructor through the web, they should enter the laboratory through the door and provide their user name, password, and the URL address of the Y Science server at the card reader. Details on accessing Virtual Physical Science can be found in the Accessing VPS user guide found on the CD. Getting Started xi sx07CAGr8_VPhyLab_01.fm Page 1 Thursday, July 19, 2007 8:43 AM Name ___________________________ Date ___________________ Class ____________ Lab 1: Introduction to Scientific Inquiry Introduction to Scientific Inquiry Purpose To show how the processes of scientific inquiry can help you learn about the natural world Background Scientific inquiry is a way of learning about the natural world by gathering information and then trying to make sense of it. Scientific inquiry does not always occur in the same way, but certain steps are often involved. Some steps that scientists often use in their investigations are posing questions, developing hypotheses, designing experiments, collecting and interpreting data, drawing conclusions, and communicating ideas and results. Skills Focus Posing questions, developing hypotheses, designing an experiment, collecting and interpreting data, interpreting a graph, predicting, drawing conclusions, communicating Introduction © Pearson Education, Inc. All rights reserved. 1. Posing Questions Have you ever observed how a gas in a balloon acts when heated? What did you see? What questions could you ask about how changing temperature affects the gas in a balloon? (Remember, the questions you ask should be questions that can be answered by making observations.) __________________________________________________________________ 2. Developing Hypotheses Scientific inquiry moves forward when ideas can be tested. Your first step is to develop a hypothesis. A hypothesis is a possible answer to a scientific question or an explanation for a set of observations. Your hypothesis is not a fact. It must be tested. Your observations may support your hypothesis or they may not. If they do not support your hypothesis, you have not wasted your time. You have learned that your hypothesis is not correct and that you must explore further. Write a hypothesis about the volume of a balloon when the temperature of the gas in a balloon is changed. __________________________________________________________________ Introduction to Scientific Inquiry 1 sx07CAGr8_VPhyLab_01.fm Page 2 Thursday, July 19, 2007 8:43 AM Introduction to Scientific Inquiry Name ___________________________ Date ___________________ Class ____________ 3. Designing an Experiment Scientists test hypotheses by designing controlled experiments. A controlled experiment is one in which all but one of the variables remain the same. The variable that you change in your experiment is the controlled parameter. The variable that changes because of what you do is the variable parameter. a. How would you design a controlled experiment to test your hypothesis about the balloon? _______________________________________________________________ b. What is the controlled parameter in your experiment? _______________________________________________________________ c. What is the variable parameter in your experiment? _______________________________________________________________ 4. Collecting and Interpreting Data Observations can be qualitative or quantitative. Qualitative observations are descriptions, such as notes you might make in a journal or notebook. Quantitative observations are measurements that are usually recorded in tables with their units. Scientists make it easier to share data by using the same system of measurement with standard units of measure. In your experiment the unit for volume is cubic centimeters (cm3). The unit for temperature is degrees Celsius (°C). Procedure 1. Start Virtual Physical Science and select Introduction to Scientific Inquiry from the list of assignments. The lab will open in the Gases laboratory. 3. Observe the current volume and temperature of the gas and record them in the table. Now, click on the 1 in the temperature window. The digit should turn green. Type 2, so that the temperature is now 200°C. Record the new volume and temperature in the table. Repeat this step again but type 3 in the temperature window. Again, record your data. Continue to increase the temperature by 100°C each time and record your data until you reach 700°C. Temperature (°C) 2 Introduction to Scientific Inquiry Volume (cm3) © Pearson Education, Inc. All rights reserved. 2. Note that the balloon in the chamber is filled with a gas at a temperature of 100°C and a pressure of 101.3 kPa. The volume of the gas is 1531 cm 3. sx07CAGr8_VPhyLab_01.fm Page 3 Thursday, July 19, 2007 8:43 AM Name ___________________________ Date ___________________ Class ____________ Analyze and Conclude Introduction to Scientific Inquiry 1. Communicating The data you placed in the data table is quantitative data. Qualitative data would be your written observations about what happened in the experiment. Write a short summary of what you observed. __________________________________________________________________ 2. Making a Graph You can plot the information in the data table on a graph. Plot the controlled parameter on the horizontal axis and the variable parameter on the vertical axis. © Pearson Education, Inc. All rights reserved. a. What measurement (with its units) is plotted on the horizontal axis (x-axis)? _______________________________________________________________ b. What measurement (with its units) is plotted on the vertical axis (y-axis)? _______________________________________________________________ c. At 450°C, what is the approximate volume? _______________________________________________________________ d. Predicting What will be the approximate volume when the temperature is 1000°C? _______________________________________________________________ Introduction to Scientific Inquiry 3 sx07CAGr8_VPhyLab_01.fm Page 4 Thursday, July 19, 2007 8:43 AM Introduction to Scientific Inquiry Name ___________________________ Date ___________________ Class ____________ 3. Drawing Conclusions After scientists interpret their data, they draw conclusions about their hypothesis. A conclusion states whether the data support the hypothesis. Review your hypothesis. Look at the information in the table and the graph. What conclusion can you make about your hypothesis? __________________________________________________________________ 4. Communicating An important part of scientific inquiry is communicating. Communicating is sharing ideas and conclusions with others through writing and speaking. It is also sharing the process you used in your inquiry. Assume you are a television reporter and are assigned to do a story about the experiment you just completed. Write a short summary for your television audience describing the process of scientific inquiry. Use the procedure and results of this experiment as an example. © Pearson Education, Inc. All rights reserved. 4 Introduction to Scientific Inquiry sx07CAGr8_VPhyLab_02.fm Page 5 Wednesday, August 8, 2007 2:09 PM Name ___________________________ Date ___________________ Class ____________ Lab 2: Making Sense of Density Purpose To discover whether different metals have different densities Background A kilogram of gold takes up much less space than a kilogram of feathers because gold has a much higher density than feathers. Density is the amount of mass of a substance in a given volume. Often, density is expressed as the number of grams in one milliliter (g/mL). In order to calculate the density of a substance, you need to know both the mass and the volume. The mathematical formula for density is shown below. Mass Density --------------------Volume or dm ---V Making Sense of Density The formula shows that you find density by dividing the mass by the volume. You can calculate the volume of a spherical object (ball) using this formula: 3 Volume of a ball 4--- r , where “r” is the radius 3 This will give you the volume of the solid balls from just knowing their radii. It is also possible to calculate the volume by measuring the amount of fluid displaced by the object in a known volume. 1 mL is equal to 1 cm 3. The unit for density in this lab will be g/mL. Skills Focus Calculating, relating cause and effect, drawing conclusions Procedure © Pearson Education, Inc. All rights reserved. 1. Start Virtual Physical Science and select Making Sense of Density from the list of assignments. The lab will open in the Density laboratory. 2. Find the gold ball on the lab wall. Pick up the ball and drag it to the spotlight on the balance. Record the mass in the table. 3. The approximate radius of the gold ball is 1.6 cm. Using this information and the formulas given earlier, calculate the volume of the ball and the density of the gold. Record your answers in the table. 4. Repeat the experiment for aluminum (Al). You can also calculate the volume of the ball by measuring the volume of water displaced by the object. On the laboratory bench, you can see a 250 mL graduated cylinder filled with water. Click on the cylinder to see a zoomed-in view of the level of the water. Record the initial volume of the water in the table. Making Sense of Density 5 sx07CAGr8_VPhyLab_02.fm Page 6 Wednesday, August 8, 2007 2:09 PM Name ___________________________ Date ___________________ Class ____________ 5. Drag the aluminum ball to the top of the cylinder and drop it in the cylinder of water. Click the green Release button to let the ball fall into the water. Look at the close-up view window to note the new volume of the water. Record the final volume in the table. The volume of your aluminum ball will be the difference of the final volume of the water with the ball and the initial volume of just the water. Record the calculated volume of the ball in the table. Ball Mass of Ball (g) Volume of Water (mL) Volume of Water and Ball (mL) Volume of Ball Density (g/mL) Au Making Sense of Density Al Analyze and Conclude 1. Applying Concepts If both of the objects were approximately the same size, or volume, why did they have such different masses? __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ 3. Drawing Conclusions Aluminum and its alloys are the primary metals used in the construction of airplanes. Does this make sense given its density? Why? __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ 6 Making Sense of Density © Pearson Education, Inc. All rights reserved. 2. Predicting Look through all the different options of balls. Which do you think is the most dense and which would be the least dense? How could you actually determine that? __________________________________________________________________ sx07CAGr8_VPhyLab_03.fm Page 7 Thursday, July 19, 2007 8:44 AM Name ___________________________ Date ___________________ Class ____________ Lab 3: Investigation of Gas Pressure and Mass Purpose To determine the relationship between the internal pressure of a gas and an applied external pressure Background An understanding of pressure is an important part of your understanding of the behavior of gases. Pressure is defined as force per unit area. The pressure a gas exerts is determined by temperature, external pressure, volume, and the number of particles of gas present. This experiment will help you become more familiar with pressure and how it is measured. Skills Focus Observing, calculating, predicting Procedure 1. Start Virtual Physical Science and select Investigation of Gas Pressure and Mass from the list of assignments. The lab will open in the Gases laboratory. Note that in this experiment the internal pressure of the gas is the sum of the pressure exerted by the gas and the pressure of any mass added to the piston. If no mass is added to the piston, the internal pressure is equal to the external pressure. Investigation of Gas Pressure and Mass 2. Click the green Piston button to move the piston onto the cylinder. Record the mass in tons, the external pressure (in pounds per square inch, or psi) and the internal pressure (in psi) in the table. (1 psi = 6.89 kPa) © Pearson Education, Inc. All rights reserved. 3. Click on the tenths digit for the mass (the .0) on the Force Controller and enter a 5. This will add 0.5 ton of mass to the piston. Record the mass, external pressure (in psi) and internal pressure (in psi) in the table. Mass (tons) External Pressure (psi) Internal Pressure From Meter (psi) Calculated Internal Pressure (psi) Investigation of Gas Pressure and Mass 7 sx07CAGr8_VPhyLab_03.fm Page 8 Thursday, July 19, 2007 8:44 AM Name ___________________________ Date ___________________ Class ____________ Analyze and Conclude 1. Calculating You can calculate the pressure exerted by 0.5 ton and compare it with the pressure obtained in the experiment. To do this, you need to convert the mass in tons to pounds. Then find the area of the piston in square inches. With the mass in pounds and the area in square inches, you can calculate the pounds pressing on each square inch (psi). First, convert tons to pounds. One ton is 2000 pounds. How many pounds is 0.5 ton? __________________________________________________________________ 2 2. To calculate the area of the circular piston use the equation A r , where A is the area, is 3.14 and r is the radius. The diameter of the piston is 15 cm. Recall that the diameter of a circle is twice the radius. What is the radius of the piston (in cm)? __________________________________________________________________ 3. To calculate pressure in pounds per square inch, the radius of the piston must be changed from centimeters to inches. 1 inch = 2.54 cm, so the radius of the piston in inches is calculated like this: 7.5 cm ----------------------------- 2.95 in 2.54 cm/in 2 4. The pressure exerted on the piston by the added mass in pounds per square inch (psi) can be determined by dividing the mass in pounds (answer to Question 1) by the area in square inches (answer to Question 3). What is the pressure exerted by the added mass in psi? __________________________________________________________________ 5. The internal pressure of the gas is the sum of the external pressure and the pressure exerted by the added mass. This is the sum of the external pressure recorded in the table and the answer to Question 4. What is the calculated internal pressure? Record your answer in the table. Compare your calculated answer to the internal pressure meter answer. How do they compare? __________________________________________________________________ __________________________________________________________________ 8 Investigation of Gas Pressure and Mass © Pearson Education, Inc. All rights reserved. Investigation of Gas Pressure and Mass Now use the equation A r to calculate the area of the piston in square inches (in2). __________________________________________________________________ sx07CAGr8_VPhyLab_03.fm Page 9 Thursday, July 19, 2007 8:44 AM Name ___________________________ Date ___________________ Class ____________ 6. Applying Concepts A bike tire is usually inflated to 40 psi as measured on a tire gauge. This measurement represents the difference between the internal pressure pushing on one end of the gauge and the air pressure pushing on the other end of the gauge. To obtain the internal pressure, add the air pressure (14.7 psi) to the gauge pressure (40 psi). The internal pressure is 54.7 psi. How does the pressure calculated in 5 compare to the pressure in a bike tire? __________________________________________________________________ __________________________________________________________________ 7. a. Calculate the internal pressure (in psi) when 2.5 tons (the mass of a small car) is placed on the piston. (Repeat Questions 1–5 using 2.5 tons instead of 0.5 ton.) _______________________________________________________________ b. How does your calculated answer compare to the internal pressure meter when you add 2.5 tons of mass? Record your data in the table. _______________________________________________________________ c. The gauge pressure for a tire on a passenger car is usually 32 psi. Calculate the internal pressure for a car tire and compare it to your answer for 7a. _______________________________________________________________ _______________________________________________________________ © Pearson Education, Inc. All rights reserved. Investigation of Gas Pressure and Mass Investigation of Gas Pressure and Mass 9 sx07CAGr8_VPhyLab_04.fm Page 10 Thursday, July 19, 2007 8:45 AM Name ___________________________ Date ___________________ Class ____________ Lab 4: Pressure and Volume of a Gas Purpose To discover how changing the pressure on a gas-filled balloon affects the volume of the balloon Background Robert Boyle, a philosopher and theologian, studied the properties of gases in the 17th century. He noticed that gases behave like springs. When compressed or expanded, gases tend to ‘spring’ back to their original volume. Boyle studied the relationship between the pressure and volume of a gas and summarized his results in what has become known as Boyle’s Law. You can make observations similar to those of Robert Boyle by changing the pressure of a gas and observing what happens to its volume. Skills Focus Graphing, predicting, interpreting data, controlling variables, drawing conclusions Procedure 1. Start Virtual Physical Science and select Pressure and Volume of a Gas from the list of assignments. The lab will open in the Gases laboratory. Note that the balloon in the chamber is filled with a gas at a temperature of 25 °C. The pressure of the gas is 100 kPa. The volume of the balloon is 7436 cm 3. 3. Observe the beginning pressure and volume of the gas and record them in the table. Now, click on the 1 in the pressure window. The digit should turn green. Type 2 so that the pressure becomes 200 kPa. Record the new pressure and volume in the table. Repeat this step again but set the pressure to 300 kPa. Again, record your data. Continue to increase the pressure by 100 kPa each time and record your data until you reach 700 kPa. Pressure and Volume of a Gas Pressure (kPa) 10 Pressure and Volume of a Gas Volume (cm3) © Pearson Education, Inc. All rights reserved. 2. Predicting You are going to increase the pressure on the balloon. What will happen to the volume of the balloon? Record your prediction. __________________________________________________________________ sx07CAGr8_VPhyLab_04.fm Page 11 Thursday, July 19, 2007 8:45 AM Name ___________________________ Date ___________________ Class ____________ Analyze and Conclude 1. Graphing Make a line graph of the data in the table. Show pressure in kPa on the horizontal axis and volume in cm3 on the vertical axis. 2. Drawing Conclusions Did your results support your prediction? Explain. __________________________________________________________________ __________________________________________________________________ 3. Interpreting Graphs Is the relationship between pressure and volume linear or nonlinear? __________________________________________________________________ Decrease the pressure on the balloon to check your prediction. Pull down on the lever on the pressure controller until the tens digit turns blue and hold it. This causes the pressure to decrease. Observe the balloon volume as the pressure decreases. Pressure and Volume of a Gas © Pearson Education, Inc. All rights reserved. 4. Predicting How would the volume of the gas be affected if the pressure were decreased? __________________________________________________________________ Pressure and Volume of a Gas 11 sx07CAGr8_VPhyLab_05.fm Page 12 Thursday, July 19, 2007 8:46 AM Name ___________________________ Date ___________________ Class ____________ Pressure and Temperature of a Gas Lab 5: Pressure and Temperature of a Gas Purpose To explore how changing the temperature of a fixed volume of gas affects the pressure of the gas Background The temperature of a gas is related to the motion of the particles of a gas. As temperature increases, the gas molecules move faster. What effect does the motion of gas molecules have on the pressure exerted by the gas? By changing the temperature of the gas you will change the motion of the particles and can observe what happens to the pressure. Skills Focus Graphing, predicting, interpreting data, controlling variables, drawing conclusions Procedure 1. Start Virtual Physical Science and select Pressure and Temperature of a Gas from the list of assignments. The lab will open in the Gases laboratory. Note that the chamber is filled with a gas at a temperature of 100°C. The pressure of the gas is 310.3 kPa. Its volume is 1000 cm3. 3. Record the beginning temperature and pressure of the gas in the table. Click on the 1 in the temperature window. The digit should turn green. Type 2 so that the temperature is 200°C. Record the new pressure and temperature in the table. Repeat this step again but set the temperature to 300°C. Again, record your data. Continue to increase the temperature by 100°C each time and record your data until you reach 700°C. Temperature (°C) 12 Pressure and Temperature of a Gas Pressure (kPa) © Pearson Education, Inc. All rights reserved. 2. Predicting You are going to increase the temperature of the gas in the chamber. What effect will the change in temperature have on the pressure? Record your prediction. __________________________________________________________________ sx07CAGr8_VPhyLab_05.fm Page 13 Wednesday, August 8, 2007 2:11 PM Name ___________________________ Date ___________________ Class ____________ Analyze and Conclude Pressure and Temperature of a Gas 1. Graphing Make a line graph of the data obtained in Step 3. Show temperature in °C on the horizontal axis and pressure in kPa on the vertical axis. 2. Drawing Conclusions Did your results support your prediction? Explain. __________________________________________________________________ 3. Interpreting Graphs Is the relationship between temperature and pressure linear or nonlinear? __________________________________________________________________ © Pearson Education, Inc. All rights reserved. 4. Predicting How would the pressure of the gas change if the temperature were decreased? __________________________________________________________________ To check your prediction, decrease the temperature in the container by pulling down on the lever in the temperature controller until the tens digit turns blue and holding the lever. Observe the pressure as the temperature decreases. Pressure and Temperature of a Gas 13 sx07CAGr8_VPhyLab_06.fm Page 14 Wednesday, August 8, 2007 2:18 PM Name ___________________________ Date ___________________ Class ____________ Lab 6: Changes Between a Solid and a Liquid Purpose To determine how temperature changes as ice is heated and becomes liquid water Background Changes Between a Solid and a Liquid Depending on the temperature, most substances can exist as both a solid and a liquid. A substance in its liquid state has more thermal energy than it has in its solid state. The temperature at which a substance changes from a solid to a liquid is the melting point of the substance. The melting point is a characteristic property of a substance. Chemists often use the melting point to help identify or classify a substance. Skills Focus Graphing, interpreting graphs, applying concepts, drawing conclusions Procedure 2. Observe the temperature of the ice/water mixture graphed in the plot window as a function of time until the blue graph line reaches four (4) minutes. Click Save on the Plot window. A blue link will appear in the lab book. Click on the link in the lab book to display the graph for the time 0–4 minutes. 14 Changes Between a Solid and a Liquid © Pearson Education, Inc. All rights reserved. 1. Start Virtual Physical Science and select Changes Between a Solid and a Liquid from the list of assignments. The lab opens in the Calorimetry laboratory. A coffee cup calorimeter filled with an ice/water mixture is on the lab bench. The ice has just been placed in the cup, so the temperature of the water is initially lowering as the ice cools the water down. The ice water is being stirred and as time passes the ice will begin to melt as the cup heats up. You will analyze the graph of the temperature to determine when the melting occurs. Click the clock on the wall labeled Accelerate to accelerate the laboratory time. Click on the lab book to open it. Click the Plot window to bring it to the front. sx07CAGr8_VPhyLab_06.fm Page 15 Wednesday, August 8, 2007 2:18 PM Name ___________________________ Date ___________________ Class ____________ Analyze and Conclude 1. Graphing On the grid below, make a sketch of what you observed of the temperature of the water as it changed with time. Label the axes. Label the part of the line where the water is a mixture of ice and liquid water. Label the part of the line where the water is all liquid. Changes Between a Solid and a Liquid 2. a. Interpreting Graphs What is the state or states of the water in the calorimeter at 0°C? _______________________________________________________________ © Pearson Education, Inc. All rights reserved. b. What is the state of the water at 3 minutes? _______________________________________________________________ c. What happens to the temperature during the time when ice is still present in the water? Explain _______________________________________________________________ _______________________________________________________________ _______________________________________________________________ _______________________________________________________________ d. What happens to the temperature after all of the ice has melted? Why? _______________________________________________________________ _______________________________________________________________ _______________________________________________________________ Changes Between a Solid and a Liquid 15 sx07CAGr8_VPhyLab_07.fm Page 16 Wednesday, August 8, 2007 2:19 PM Name ___________________________ Date ___________________ Class ____________ Lab 7: Changes Between a Liquid and a Gas Purpose To investigate how the temperature changes as liquid water is heated until it becomes water vapor Background The particles that make up a gas have more thermal energy than particles of the same substance in the liquid state. The particles of a liquid are in close contact with each other while gas particles are spaced significantly further apart. The transition from a liquid to a gas is known as vaporization and occurs by either evaporation or boiling. The boiling point is a characteristic property of a substance and can be used by chemists to help identify or classify the substance. The normal boiling point is the temperature at which a substance boils at sea level. At higher altitudes, where the air pressure is lower, the boiling point is lower. Skills Focus Graphing, interpreting graphs, applying concepts, relating cause and effect 1. Start Virtual Earth Science and select Changes Between a Liquid and a Gas from the list of assignments. The lab will open in the Calorimetry laboratory. A coffee cup calorimeter filled with 100 mL of water at 25°C is on the lab bench. Click the clock on the wall labeled Accelerate to accelerate the laboratory time. Click the lab book to open it. Click on the thermometer or a part of the thermometer window to bring the thermometer window to the front. Turn on the heater by clicking on the green light on the control panel labeled Heat. Finally, click on the Plot window to bring it to the front. 2. Observe the temperature of the water graphed in the Plot window as a function of time until steam begins to form above the coffee cup calorimeter. Record, in the table, the temperature at which boiling begins. Continue to observe the graph for three minutes. The graph will show you when three minutes have passed. Click Save on the Plot window. A blue link will appear in the lab book. Click on the link in the lab book to display the graph for the time 0–3 minutes. Now click the Pressure display just below the green Exit sign to display the pressure in the virtual laboratory. Record this pressure in the table. The pressure is displayed on this meter only in torr. A torr is a unit of pressure often used by chemists. 760 torr 101.3 kPa. Notice that the pressure in the laboratory may be greater or less than 760 torr, which is standard atmospheric pressure at sea level. Atmospheric pressure can vary depending on the altitude of the lab and the weather. Temperature at Boiling (°C) 16 Changes Between a Liquid and a Gas Pressure at Boiling (torr) © Pearson Education, Inc. All rights reserved. Changes Between a Liquid and a Gas Procedure sx07CAGr8_VPhyLab_07.fm Page 17 Thursday, July 19, 2007 8:47 AM Name ___________________________ Date ___________________ Class ____________ Analyze and Conclude 1. Graphing In the grid below, make a sketch of how the temperature of the water changed with time. Label the axes. Label the portion of the line where the water is a liquid. Label the portion where the water is changing to a gas. The blue graph line will appear on top of the black outline of the graph boundary. You may have to look closely to see the blue graph line. Changes Between a Liquid and a Gas 2. a. Interpreting Graphs At what temperature does steam first begin to form? _______________________________________________________________ © Pearson Education, Inc. All rights reserved. b. What is happening to the temperature of the water in the first minute as heat is being added? Why? _______________________________________________________________ _______________________________________________________________ _______________________________________________________________ c. What is happening to the temperature as the water continues to boil and the liquid water is changed to water vapor? Explain _______________________________________________________________ _______________________________________________________________ _______________________________________________________________ Changes Between a Liquid and a Gas 17 sx07CAGr8_VPhyLab_07.fm Page 18 Thursday, July 19, 2007 8:47 AM Name ___________________________ Date ___________________ Class ____________ Going Further 3. Relating Cause and Effect The average or typical air pressure at sea level is 760 torr (101.3 kPa). This pressure may vary by ±15 torr depending on the weather. In stormy weather, the pressure at sea level drops lower than 760 torr. In good weather, the pressure rises above 760 torr. The normal boiling point of water is 100°C at 760 torr or 101.3 kPa. From your observation of the boiling point and air pressure, what can you conclude? __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ 4. Applying Concepts From this observation, what would happen to the boiling point of water at the top of Mt. McKinley? (The summit of Mt. McKinley is the highest elevation in North America at 6194 m above sea level. At this altitude there is much less atmosphere above you so the air pressure is much lower.) __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ Changes Between a Liquid and a Gas © Pearson Education, Inc. All rights reserved. 18 Changes Between a Liquid and a Gas sx07CAGr8_VPhyLab_08.fm Page 19 Thursday, July 19, 2007 8:48 AM Name ___________________________ Date ___________________ Class ____________ Lab 8: Thomson and Smaller Parts of Atoms Purpose To learn how Thomson determined the charge to mass ratio of electrons Background As scientists began to explore the nature of atoms, their first discovery was that an atom contains smaller, negatively charged particles. They called these particles electrons. John Joseph (J. J.) Thomson was a physics professor at the Cavendish Laboratory in England. Thomson found that the path of a stream of electrons could be bent when placed between oppositely charged electric plates (an electric field). The path of the electrons could also be bent when placed between opposite poles of a magnet (a magnetic field). In 1897, Thomson showed that if you could measure how much a beam of electrons was bent in an electric field and in a magnetic field, you could determine the electron’s charge to mass ratio. You will complete an experiment similar to Thomson’s to understand how the scientist learned about the electron. Skills Focus Inferring, drawing conclusions Procedure 1. Start Virtual Physical Science and select Thomson and Smaller Parts of Atoms from the list of assignments. The lab will open in the Quantum laboratory. 2. What source is used in this experiment? The source is on the left. Move your cursor over it to identify it. __________________________________________________________________ What detector is used in this experiment? The detector is on the right. Move your cursor over it to identify it. __________________________________________________________________ 3. Click the On/Off button to turn on the Phosphor Screen. A window will pop up showing a close-up of the screen and the controls. The phosphor screen detects charged particles such as electrons. It glows momentarily at the positions where the particles hit the screen. What do you observe on the phosphor screen? __________________________________________________________________ Thomson and Smaller Parts of Atoms 19 Thomson and Smaller Parts of Atoms © Pearson Education, Inc. All rights reserved. What type of charge do electrons have? __________________________________________________________________ sx07CAGr8_VPhyLab_08.fm Page 20 Friday, August 10, 2007 12:39 PM Name ___________________________ Date ___________________ Class ____________ 4. To minimize overlap of windows, drag the main lab window down and left. Drag the phosphor detector screen window up and right. Click on the Grid button on the phosphor screen. The magnetic field controller is on the lab bench next to the phosphor screen. Click the button above the tens place three times to set the Magnetic Field to 30 µT. What happens to the spot from the electron gun on the phosphor screen? __________________________________________________________________ 5. Set the Magnetic Field back to zero by clicking on the button below the tens place three times and set the Electric Field to 10 V. What happens to the spot from the electron gun on the phosphor screen? __________________________________________________________________ Inferring Where should the signal on the phosphor screen be if the effects of the electric field and magnetic field are balanced? __________________________________________________________________ 6. Drawing Conclusions Increase the magnetic field strength until the spot reaches the center of the screen. Do this by clicking above the tens place and then the ones place. What magnetic field balances the effect of the electric field? __________________________________________________________________ __________________________________________________________________ Thomson and Smaller Parts of Atoms 20 Thomson and Smaller Parts of Atoms © Pearson Education, Inc. All rights reserved. Balancing the magnetic field strength with the electric field strength allowed Thomson to make mathematical calculations to determine the charge to mass ratio for an electron. This provided the evidence needed to convince scientists that atoms are made of smaller parts and that one of those parts was an electron with a negative charge. sx07CAGr8_VPhyLab_09.fm Page 21 Wednesday, August 8, 2007 2:26 PM Name ___________________________ Date ___________________ Class ____________ Lab 9: Rutherford and the Nucleus Rutherford and the Nucleus Purpose To learn how Rutherford found evidence for the nucleus of the atom Background © Pearson Education, Inc. All rights reserved. In your laboratory experiments, you have made observations and drawn conclusions from data. But imagine that you had to do your experiments in a dark room and couldn’t see the materials you were working with. Imagine that the objects you were working with were so small that they couldn’t be seen with a microscope. The early scientists who studied the atom had to work under similar conditions. They were trying to find out about a bit of matter so small that there was no hope of actually seeing it. Nevertheless, these atomic scientists were able to infer that the atom has a nucleus. A key experiment in understanding atomic structure was completed by Ernest Rutherford in 1911. He directed a beam of positively charged particles (alpha particles) through a gold foil and then onto a detector screen. Before Rutherford performed his experiment, most scientists thought that electrons were distributed in a positively charge mass like raisins in a muffin. Based on this model, Rutherford expected that almost all the positively charged particles would pass through the gold foil along a straight path. A few particles might be slightly deflected because they were attracted by the negative electrons (alpha particles have a charge of 2). Imagine his surprise when some alpha particles veered off their straight line paths at large angles. Occasionally an alpha particle was deflected back towards the source. According to the raisin muffin atomic model that Rutherford was testing, nothing in the atom was massive enough to strongly deflect an alpha particle. Rutherford said about his results that it was “almost as incredible as if you fired a 15-inch shell at a piece of tissue paper and it came back and hit you!” He inferred from the experimental data that most of the mass of an atom was concentrated in a small, positively charged nucleus at its center. This nucleus was surrounded by mostly empty space. Electrons moved around the nucleus in that space. Now you can make observations similar to Rutherford’s. Skills Focus Inferring, drawing conclusions Procedure 1. Start Virtual Physical Science and select Rutherford and the Nucleus from the list of assignments. The lab will open in the Quantum laboratory. 2. The experiment will be set up on the lab table. Point the cursor at the gray box on the left side where you should see a popup describing what this device is. What particles are emitted from this source? _________________________________________________________________ Rutherford and the Nucleus 21 sx07CAGr8_VPhyLab_09.fm Page 22 Wednesday, August 8, 2007 2:26 PM Rutherford and the Nucleus Name ___________________________ Date ___________________ Class ____________ 3. Point the cursor at the metal sample holder in the center. What metal foil is used? _________________________________________________________________ 4. Point the cursor at the detector on the right. What detector is used in this experiment? _________________________________________________________________ 5. Turn on the detector by clicking on the red/green light switch. A window will pop up showing a close-up of the screen and the controls. The phosphor screen detects charged particles such as alpha particles. It glows momentarily at the positions where the particles impact the screen. The signal in the middle of the screen represents the alpha particles coming straight through the gold foil undeflected or only slightly deflected. What other signals do you see on the phosphor detection screen? _________________________________________________________________ Inferring What do these signals represent? _________________________________________________________________ Click the Persist button (the dotted arrow) on the phosphor detector screen. According to the raisin muffin model, what is causing the deflection of the alpha particles? _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ 6. Now you will make observations at different angles of deflection. Click on the main window to bring it to the front. Click and drag the phosphor detection screen by its base and move it to the spotlight in the top right corner of the table. The Persist button should still be on. Observe the number of hits in this position as compared to the first detector position. _________________________________________________________________ 7. Move the detector to the top center spotlight position at a 90-degree angle to the foil holder. Observe the number of hits in this spotlight position as compared to the first detector position. _________________________________________________________________ 22 Rutherford and the Nucleus © Pearson Education, Inc. All rights reserved. What can you observe about the rate at which the positively charged particles (alpha particles) hit the screen? _________________________________________________________________ sx07CAGr8_VPhyLab_09.fm Page 23 Thursday, July 19, 2007 8:48 AM Name ___________________________ Date ___________________ Class ____________ Rutherford and the Nucleus 8. Analyzing Cause and Effect Move the detector to the top left spotlight position. Observe the number of hits in this spotlight position as compared to the first detector position. What could cause the alpha particles to deflect backwards? _________________________________________________________________ 9. How do these results disprove the raisin muffin model? Keep in mind that there are 1,000,000 alpha particles passing through the gold foil per second. _________________________________________________________________ _________________________________________________________________ 10. Are the gold atoms composed mostly of matter or empty space? _________________________________________________________________ 11. How does the Gold Foil Experiment show that almost all of the mass of an atom is concentrated in a small positively charged central atom? _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ © Pearson Education, Inc. All rights reserved. _________________________________________________________________ Rutherford and the Nucleus 23 sx07CAGr8_VPhyLab_10.fm Page 24 Wednesday, August 8, 2007 2:38 PM Name ___________________________ Date ___________________ Class ____________ Lab 10: Elements and the Periodic Table Purpose To find out what information about the elements can be obtained from the periodic table Background When you begin to study chemistry, it’s important to learn the symbols for the common elements. In this assignment, you will go into the virtual laboratory and create solutions in which metal elements are dissolved in water. A periodic table can help you identify the symbols for each of these elements. You can also obtain other information about the elements from a periodic table. Elements and the Periodic Table Skills Focus Applying concepts, drawing conclusions, classifying, making generalizations Procedure 1. Start Virtual Physical Science and select Elements and the Periodic Table from the list of assignments. The lab will open in the Inorganic laboratory. 3. Discard the test tube by either clicking on the red disposal bucket in the lower right corner of the screen or by clicking and dragging the test tube from the test tube holder and dropping it on the disposal bucket. 4. Repeat Steps 2 and 3 for each of the following elements: Sodium, Potassium, Cobalt, Copper, Chromium, Magnesium, Barium, Calcium, Vanadium, Nickel, and Aluminum. Record the symbol for each element and a description of the solution of each element in each test tube in the table. 5. When you are finished, click on the Return to Lab arrow to return to the laboratory. Then click on the door to exit the laboratory. 24 Elements and the Periodic Table © Pearson Education, Inc. All rights reserved. 2. Observing Enter the stockroom by clicking inside the Stockroom window at the upper right. Drag a test tube from the box and place it on the metal test tube stand. What is the symbol used to represent silver? Identify the bottle containing silver and click on it. This will fill the test tube with a solution containing silver. You can see a picture of it in the picture window in the lower left part of the screen. (Refer to a periodic table to learn the chemical symbol for silver.) What is the color of the solution in the test tube? Record your answers in the table below. sx07CAGr8_VPhyLab_10.fm Page 25 Thursday, July 19, 2007 8:49 AM Name ___________________________ Date ___________________ Class ____________ 6. Complete the table for each element symbol. Use a periodic table to find each element’s atomic number, atomic mass, and group number. Element Symbol Color of Solution Atomic Number Atomic Mass Group Number Silver Sodium Potassium Cobalt Copper Chromium Magnesium Elements and the Periodic Table Barium Calcium Vanadium Nickel Aluminum Analyze and Conclude 1. What information about the element does the atomic number provide? __________________________________________________________________ 2. Applying Concepts How many protons and electrons does a vanadium atom have? __________________________________________________________________ © Pearson Education, Inc. All rights reserved. 3. Why is the atomic mass of an element an average atomic mass? __________________________________________________________________ 4. Classifying All of the elements in this experiment are metals. Place each of the metals into one of these groups: alkali metals, alkaline-earth metals, transition metals, or mixed group metals. __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ 5. Drawing Conclusions What can you conclude about the metal elements whose solutions are colored and the metal group to which they belong? __________________________________________________________________ __________________________________________________________________ Elements and the Periodic Table 25 sx07CAGr8_VPhyLab_11.fm Page 26 Thursday, July 19, 2007 8:49 AM Name ___________________________ Date ___________________ Class ____________ Lab 11: Density of Solids and Liquids Problem To learn how density is determined for solids and for liquids Background Density is the mass of a substance in a given volume. The mathematical formula for density is given below. Mass Density --------------------Volume or dm ---V To calculate the density of a substance, you need to know both its mass and the volume it occupies. The formula shows that to calculate density you divide the mass by the volume. For this assignment, you will measure the masses of the substances in grams ( g) and the volumes of both the solid and the liquid in milliliters (mL). 1 mL is equal to 1 cm3. The unit for density in this lab will be g/mL. Skills Focus Problem solving, applying concepts, developing hypotheses, making generalizations Procedure Part 1 Density of a Solid Density of Solids and Liquids 2. Find the plastic sphere on the lab wall. Pick up the ball and drag it to the spotlight on the balance. Record the mass in the Solid Data and Results table. 3. On the laboratory bench, you can see a 250 mL graduated cylinder partially filled with a unique Virtual Fluid that is used only in this virtual laboratory. Click on the cylinder to see a zoomed-in view of the level of the fluid. Record the volume of the Virtual Fluid in the Solid Data and Results table. 4. Drag the plastic ball to the top of the cylinder and drop it in the cylinder of Virtual Fluid. Click the green Drop button to let the ball fall into the fluid. Look at the close-up view window to note the new volume of the fluid. Record the volume in the table. 5. Problem Solving How can you determine the volume of the plastic ball from your measurements? _________________________________________________________________ _________________________________________________________________ 26 Density of Solids and Liquids © Pearson Education, Inc. All rights reserved. 1. Start Virtual Physical Science and select Density of Solids and Liquids from the list of assignments. The lab will open in the Density laboratory. sx07CAGr8_VPhyLab_11.fm Page 27 Thursday, July 19, 2007 8:49 AM Name ___________________________ Date ___________________ Class ____________ Record the volume of the plastic sample in the Solid Data and Results table. Click the blue handle at the bottom of the cylinder to empty the contents of the cylinder. Solid Data and Results Sample Mass of Sample (g) Volume of Virtual Fluid (mL) Volume of Virtual Fluid and Sample (mL) Volume of Sample (mL) Density (g/mL) Plastic Part 2 Density of a Liquid 6. Toggle through the fluids on the Fluid Control switch with the gray arrows until you find Alcohol. Click the Full button underneath the display to select the amount of fluid to be added to the cylinder. Click the Fill button to fill the graduated cylinder with the alcohol. Click on the cylinder to see a zoomed-in view of the level of the fluid. Record the volume of the alcohol in the Liquid Data and Results table. 7. Click the Tare button on the balance. Taring the balance rezeros the balance with whatever is on it. Drag the beaker on the counter to the balance and record its mass in the Liquid Data and Results table. Drag the beaker back to the spotlight on the counter. 8. Pick up the cylinder filled with alcohol and pour it into the empty beaker. Drag the beaker to the balance and record the mass of the alcohol and beaker in the Liquid Data and Results table. Density of Solids and Liquids © Pearson Education, Inc. All rights reserved. 9. Problem Solving How can you determine the mass of the alcohol in the beaker? _________________________________________________________________ _________________________________________________________________ Record the mass of the alcohol in the Liquid Data and Results table. 10. Calculating Using the formula for density, calculate the density of the plastic ball and record the answer in the Solid Data and Results table. Similarly, calculate the density of the alcohol and record the answer in the Liquid Data and Results table. Density of Solids and Liquids 27 sx07CAGr8_VPhyLab_11.fm Page 28 Thursday, July 19, 2007 8:49 AM Name ___________________________ Date ___________________ Class ____________ Liquid Data and Results Sample Mass of Empty Beaker (g) Mass of Beaker and Sample (g) Mass of Sample (g) Volume of Sample (mL) Density (g/mL) Alcohol Analyze and Conclude 1. Applying Concepts When you determined the volume of the plastic ball, it was completely submerged. What if the ball floated at the top of the fluid and was not completely covered by the Virtual Fluid? How would this affect the measured volume of the solid? Explain. __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ 2. Applying Concepts Why do some materials float in water and others sink? __________________________________________________________________ __________________________________________________________________ Density of Solids and Liquids __________________________________________________________________ __________________________________________________________________ Test your hypothesis by pouring a sample of alcohol into the graduated cylinder and dropping the plastic ball into it. 4. Making Generalizations If you had several samples, both solids and liquids, what measurements and calculations would you need to make to determine whether a sample would float or sink when placed with the others? __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ 28 Density of Solids and Liquids © Pearson Education, Inc. All rights reserved. 3. Developing Hypotheses If the plastic ball were placed in the alcohol, would it float or sink? __________________________________________________________________ sx07CAGr8_VPhyLab_12.fm Page 29 Thursday, July 19, 2007 9:00 AM Name ___________________________ Date ___________________ Class ____________ Lab 12: Creating Chemical Compounds Purpose To determine the ratio of elements in a chemical compound Background Matter can consist of a single element, but more often matter is made up of chemical compounds. A chemical compound consists of two or more elements combined in a set ratio. A ratio compares two numbers. It tells you the amount of one item compared to the amount of another item. The formula for a chemical compound shows the ratio of the elements in the compound. For example, you are familiar with table salt, a chemical compound made from sodium (Na) and chlorine (Cl). The chemical formula for table salt is NaCl. The formula shows that the ratio of sodium atoms to chlorine atoms is 1:1. You are also familiar with a compound called rust, which is made from iron (Fe) and oxygen (O). The chemical formula for rust is Fe2O3. The small number to the right of each symbol is a subscript. The subscripts tell you that a molecule of rust contains two iron atoms (Fe) combined with three oxygen atoms (O). The ratio of iron atoms to oxygen atoms in rust is 2:3. When elements combine to form compounds, the compounds have different properties from those of the combining elements. Color is a property that can change in a chemical reaction, so a color change is evidence that a chemical reaction may have occurred. Skills Focus Observing, applying concepts, predicting Procedure 2. Enter the stockroom by clicking inside the Stockroom window. Once inside the stockroom, drag a test tube from the box and place it on the metal test tube stand. Click on the bottle of Ag solution on the shelf to add it to the test tube. Click Done to send the test tube back to the lab. If you make a mistake in selecting the correct solution, drag the test tube to the red disposal bucket and begin again. 3. Drag another test tube from the box and place it on the metal test tube stand. Click on the bottle of Pb2 solution on the shelf to add it to the test tube. Click Done to send the test tube back to the lab. Repeat this process and create test tubes containing Fe3 (not Fe2), Cu2, Pb2 (again), and Ag (again). Click Done after each test tube. Click on the Return to Lab arrow when finished with all test tubes. You should now be in the laboratory. Six test tubes should be in the test tube rack. Creating Chemical Compounds Creating Chemical Compounds © Pearson Education, Inc. All rights reserved. 1. Start Virtual Physical Science and select Creating Chemical Compounds from the list of assignments. The lab will open in the Inorganic laboratory. 29 sx07CAGr8_VPhyLab_12.fm Page 30 Wednesday, August 8, 2007 2:42 PM Name ___________________________ Date ___________________ Class ____________ 4. Click on the handle just above the periodic table to pull down the TV screen. The screen will display the chemical formula of the compound in the test tube as you move the cursor over a test tube. Observe the changes that occur in the test tube in the display in the lower left corner. Notice the changes in chemical formulas on the TV screen above. Move the hand over the first test tube on the left. Observe that the solution is clear and colorless in the lower left window and that the screen shows Ag. 5. Drag the first test tube (Ag) from the blue test tube rack to the metal test tube stand on the lab bench. Click the bottle labeled NaCl on the top shelf. Notice the changes in the test tube and in the screen. The solution changes from colorless to white and the screen shows AgCl. In this compound the ratio of Ag to Cl is 1:1. Record the formula, the color before reaction, the color after reaction, and the ratio in the table on the next page. Drag the test tube to the red disposal bucket on the lower right. Do NOT click on Clear All. 6. Drag the second test tube (Pb2) from the blue rack to the metal stand and click the bottle labeled NaCl on the top shelf. What changes do you observe in the test tube and in the screen? Record the color before, the color after, and the ratio in the table. Drag the test tube to the red disposal bucket. 7. Drag the third test tube (Fe3) from the blue rack to the metal stand but this time click the bottle labeled Na2S on the top shelf. Record the color before, the color after, and the ratio in the table. Drag the test tube to the red disposal bucket. Repeat for the fourth (Cu2) and fifth (Pb2) test tubes adding Na2S in each case. Record the color before, the color after, and the ratio in the table. Drag the test tubes to the red disposal bucket. Click the bottle labeled Na2S. Record the color before, the color after, and the ratio in the table. Drag the test tube to the red disposal bucket. Creating Chemical Compounds If you leave the spoon made of silver in mayonnaise, the silver metal turns dark. This is because mayonnaise is made from eggs which contain sulfur. The silver of the spoon and the sulfur from the eggs in the mayonnaise form the same compound you just created. The compound is called silver sulfide (Ag2S). The silver sulfide that forms on silver spoons and other silver objects is called tarnish. To remove tarnish, you must use a special cleaner and polish the object with a soft cloth. 30 Creating Chemical Compounds © Pearson Education, Inc. All rights reserved. 8. Predicting Drag the last test tube (Ag) to the rack. From your observations of the last three solutions, what color do you predict when Na2S is added to the Ag solution? __________________________________________________________________ sx07CAGr8_VPhyLab_12.fm Page 31 Thursday, July 19, 2007 9:00 AM Name ___________________________ Test Tube Formula From Screen Date ___________________ Color Before Color After Class ____________ Ratio Analyze and Conclude 1. Infer from your data what must be the charge of the oxygen ion, if lead forms the compound PbO? __________________________________________________________________ 2. Could the compound CuFe form? Explain your answer. __________________________________________________________________ Creating Chemical Compounds © Pearson Education, Inc. All rights reserved. 3. Tin (Sn) forms the ion Sn4+. What must be the formula for tin chloride? __________________________________________________________________ Creating Chemical Compounds 31 sx07CAGr8_VPhyLab_13.fm Page 32 Thursday, July 19, 2007 9:00 AM Name ___________________________ Date ___________________ Class ____________ Names and Formulas of Ionic Compounds Lab 13: Names and Formulas of Ionic Compounds Purpose To investigate how ions combine to form ionic compounds and learn how to name and write the formulas for these compounds Background Skills Focus Applying concepts Procedure 1. Start Virtual Physical Science and select Names and Formulas of Ionic Compounds from the list of assignments. The lab will open in the Inorganic laboratory. 2. Enter the stockroom by clicking inside the Stockroom window at the upper right of the lab. Once inside the stockroom, drag a test tube from the box and place it on the metal test tube stand. Click on the bottle of Ag ion solution on the shelf to add it to the test tube. Click Done to send the test tube back to the lab. Click on the Return to Lab arrow. 32 Names and Formulas of Ionic Compounds © Pearson Education, Inc. All rights reserved. An ion is an atom or group of atoms that has a positive or negative charge. Positive ions are formed when an atom loses one or more electrons. Negative ions are formed when an atom gains one or more electrons. Ions that contain only one atom are known as monatomic ions. Ions that contain more than one atom are called polyatomic ions. When positive and negative ions combine to form an ionic compound, the ratio of the positive ion to negative ion is such that the charges on the ions are balanced. That means that all the charges add up to zero and the compound has no charge. For example, the charge on a sodium ion is 1 (Na+). The charge on a chloride ion is 1– (Cl–). The compound formed between these two ions is sodium chloride with the formula NaCl. The subscripts in a formula tell you how many atoms of an element are needed to balance the positive and negative charges. In NaCl the subscripts are understood to be one. The 1+ charge on one sodium ion balances the 1– charge on one chloride ion. When the magnesium ion (Mg2+) and the bromide ion (Br–) combine, the formula for the compound formed is MgBr2. The subscript 2 is required on the bromide ion. Two negatively charged bromide ions (2 1) are needed to balance the 2 charge of one magnesium ion. The name of the compound is magnesium bromide. sx07CAGr8_VPhyLab_13.fm Page 33 Wednesday, August 8, 2007 2:46 PM Name ___________________________ Date ___________________ Class ____________ Names and Formulas of Ionic Compounds 3. Place the test tube containing the Ag solution in the metal test tube stand. Click on the Divide button on the bottom (with the large red arrow) four times to make four additional test tubes containing Ag. With one test tube in the metal stand and four duplicates in the blue rack, click on the Na2S bottle located on the lab bench to add Na2S solution. The solution contains both Na and S2 ions, but the S2 ion is what will combine, as indicated in the table below. Observe what happens in the window at the bottom left. Record your observation in the Observation Table below. If the solution remains the same, record NR, for no reaction. Drag this test tube to the red disposal bucket on the right. 4. Place a second Ag tube from the blue rack on the metal stand. This time add NaCl. Record your observations and discard the tube. Use the next Ag tube, but add Na2SO4. Record your observations. Use the next Ag tube, but add NaOH, and record your observations. With the last Ag tube add Na2CO3 and record your observations. When you are finished, click on the red disposal bucket to clear the lab. 5. Return to the stockroom and repeat Steps 3 and 4 using Pb2, Fe3, and Cu2. © Pearson Education, Inc. All rights reserved. Analyze and Conclude In the tables below, you will be using the data you have collected to determine the compound formulas and names. The cells of the first column of the three tables contain: (1) the label from the bottle used, (2) the negative monatomic or polyatomic ion (with the charge) to be used in the chemical formula, and (3) the name of the ion or polyatomic ion to be used in the name. The cells in the top row of each table contain: (1) the positive ion (with the charge) to be used in the chemical formula, and (2) the name of the element to be used in the chemical name. Using this information, write in the Chemical Formula Table the correct chemical formula for each combination that produced a reaction. Write in the Chemical Name Table the correct chemical name for each combination that produced a reaction. In all three tables write NR for each combination that did not produce a chemical reaction. Make certain that you balance the positive and negative charges by using subscripts in the chemical formula. If more than one polyatomic ion is required in a formula, place parentheses around it. For example, the positive aluminum ion (Al3) and the negative polyatomic ion sulfate (SO42) form the compound aluminum sulfate. The chemical formula for aluminum sulfate is Al 2(SO4)3 because 2 (3) for the aluminum ion is 6 and 3 (2) for the sulfate ion is 6. The 6 and 6 add to zero charge for the compound. Names and Formulas of Ionic Compounds 33 sx07CAGr8_VPhyLab_13.fm Page 34 Thursday, July 19, 2007 9:00 AM Name ___________________________ Date ___________________ Class ____________ Observation Table Names and Formulas of Ionic Compounds Ag silver Pb2 lead Fe3 iron Cu2 copper Na2S (S2) sulfide NaCl (Cl) chloride Na2SO4 (SO42) sulfate NaOH (OH) hydroxide Na2CO3 (CO32) carbonate Chemical Formula Table Ag silver Pb2 lead Fe3 iron Cu2 copper Na2S (S2) sulfide NaCl (Cl) chloride Na2SO4 (SO42) sulfate Na2CO3 (CO32) carbonate 34 Names and Formulas of Ionic Compounds © Pearson Education, Inc. All rights reserved. NaOH (OH) hydroxide sx07CAGr8_VPhyLab_13.fm Page 35 Wednesday, August 8, 2007 2:46 PM Name ___________________________ Date ___________________ Class ____________ Chemical Name Table Pb2 lead Fe3 iron Cu2 copper Names and Formulas of Ionic Compounds Ag silver Na2S (S2) sulfide NaCl (Cl) chloride Na2SO4 (SO42) sulfate NaOH (OH) hydroxide Na2CO3 (CO32) carbonate 1. The sulfate ion has the formula SO42. What are the formulas for the compounds made when the sulfate ion combines with Ag, Pb2 and Fe3? __________________________________________________________________ © Pearson Education, Inc. All rights reserved. 2. What are the names for the following compounds: CaS, Mg(OH) 2, KOH? __________________________________________________________________ Names and Formulas of Ionic Compounds 35 sx07CAGr8_VPhyLab_14.fm Page 36 Thursday, July 19, 2007 9:01 AM Name ___________________________ Date ___________________ Class ____________ Lab 14: Describing Chemical Reactions Purpose To represent double replacement reactions by balanced chemical equations Describing Chemical Reactions Background A chemical equation is a shorthand way to show what happens in a chemical reaction. In chemical equations, chemical symbols and formulas are used instead of words. The formulas of the reactants (the substances you start with) are placed on the left side of a right-pointing arrow. The products (the new substances formed by the reaction) are placed on the right side of the arrow. In this experiment, you will observe double replacement reactions. In a double replacement reaction, ions in one compound appear to “trade places” with ions in another compound. The general form of a double replacement equation is AB CD → CB AD. A and C represent positive ions. B and D represent negative ions. Note that in the equation, ions A and C trade places. Skills Focus Applying concepts, predicting Procedure 1. Start Virtual Physical Science and select Describing Chemical Reactions from the list of assignments. The lab will open in the Inorganic laboratory. 3. Drag the test tube containing the Ag+ from the blue rack to the metal test tube stand. Click on the NaOH bottle on the reagent shelf. Observe what happens in the window at the bottom left. Record your observation. Drag this test tube to the red disposal bucket on the right. __________________________________________________________________ __________________________________________________________________ 36 Describing Chemical Reactions © Pearson Education, Inc. All rights reserved. 2. Click in the Stockroom. Drag a test tube from the box and place it on the metal test tube stand. Click on the bottle of Ag+ metal ion solution on the shelf to add it to the test tube. Click Done to send the test tube back to the lab. Click on the Return to Lab arrow. sx07CAGr8_VPhyLab_14.fm Page 37 Thursday, July 19, 2007 9:01 AM Name ___________________________ Date ___________________ Class ____________ 4. The silver ion solution obtained from the stockroom is silver nitrate (AgNO3). When it is mixed with sodium hydroxide (NaOH), the chemical reaction that occurs can be described in words as follows: Silver nitrate reacts with sodium hydroxide to form sodium nitrate and silver hydroxide. The description can also be written in chemical formulas as follows: AgNO3 + NaOH → NaNO3 + AgOH(s) The (s) after AgOH indicates that the solution turned cloudy because a solid precipitate of AgOH formed. The equation is balanced. The same number and kind of elements are on the left and on the right of the arrow. Note that as a result of the reaction, the Ag+ ion and the Na+ ion “traded places.” This is a double replacement reaction. Describing Chemical Reactions 5. Return to the Stockroom. Drag a test tube from the box and place it on the metal test tube stand. Click on the bottle of Pb2+ metal ion solution on the shelf to add it to the test tube. Click Done to send the test tube back to the lab. Click on the Return to Lab arrow. 6. Drag the test tube containing Pb2+ from the blue rack to the metal test tube stand. Click on the Na2CO3 bottle on the reagent shelf. Observe what happens in the window at the bottom left. Record your observation. Drag this test tube to the red disposal bucket on the right. __________________________________________________________________ Analyze and Conclude 1. Applying Concepts The Pb2+ solution is lead nitrate, Pb(NO3)2. When Pb(NO3)2 is mixed Na2CO3 the chemical reaction is described in words as follows: © Pearson Education, Inc. All rights reserved. Lead nitrate reacts with sodium carbonate to form sodium nitrate and lead carbonate. Write a balanced chemical equation using chemical formulas to represent this chemical reaction. Note the charges on the ions: Pb2+, NO3, Na+, and CO32. You must balance the charges of the ions when writing the formulas for the compounds. When you have written the complete equation, balance the elements on both sides of the arrow. Describing Chemical Reactions 37 sx07CAGr8_VPhyLab_14.fm Page 38 Thursday, July 19, 2007 9:01 AM Name ___________________________ Date ___________________ Class ____________ 2. Predicting Suppose that silver nitrate solution (AgNO3) and sodium sulfide solution (Na2S) were mixed. Write a word description of the double replacement reaction that would occur. __________________________________________________________________ 3. Write a balanced chemical equation using chemical formulas to represent the reaction described in 2. The sulfide ion is S2–. __________________________________________________________________ 4. You can observe the chemical reaction in 3 by obtaining Ag+ from the Stockroom and mixing it with Na2S. Record your observations. __________________________________________________________________ Describing Chemical Reactions __________________________________________________________________ © Pearson Education, Inc. All rights reserved. 38 Describing Chemical Reactions sx07CAGr8_VPhyLab_15.fm Page 39 Thursday, July 19, 2007 9:02 AM Name ___________________________ Date ___________________ Class ____________ Lab 15: Using Energy to Observe Chemical Changes Purpose To measure temperature changes in a chemical reaction and infer whether the reaction is endothermic or exothermic Background Energy changes occur during chemical reactions. Some reactions absorb energy. Energy must be added to these reactions to cause them to occur. Reactions that absorb energy are known as endothermic reactions. Cooking food is an example of an endothermic reaction. Other reactions release energy. Reactions that release energy are known as exothermic reactions. Burning fuel to drive a car is an example of an exothermic reaction. Skills Focus Calculating, classifying, applying concepts Procedure 1. Start Virtual Physical Science. Select Using Energy to Observe Chemical Changes from the list of assignments. The lab will open in the Calorimetry laboratory. 2. A bottle of sodium chloride (NaCl) is on the lab bench. A weighing paper is on the balance with approximately 2 g of sodium chloride (NaCl) on the paper. © Pearson Education, Inc. All rights reserved. Using Energy to Observe Chemical Changes 3. The calorimeter on the lab bench contains 100 cm3 of water. Click the Lab Book to open it. Make certain the stirrer is On. You should be able to see the stirrer shaft rotating. In the thermometer window, click Save to begin recording data. Allow 20–30 seconds to obtain a baseline temperature of the water. 4. Drag the weighing paper with the sample to the calorimeter until it snaps in place. Pour the sample into the calorimeter. You can click on the Accelerate button (the clock) to accelerate the time in the laboratory. Observe the change in temperature until it levels off and then record data for an additional 20–30 seconds. Click Stop. A blue data link will appear in the Lab book. Click the blue data link and record the initial and final water temperatures in the table below. Click the red disposal bucket to clear the lab. 5. Click on the Stockroom to enter. Click on the clipboard and select Preset Experiment #7: Heat of Solution NaNO3. Click Return to Lab. Repeat the experiment with sodium nitrate (NaNO3). Record the initial and final temperatures in the table. Click the red disposal bucket to clear the lab. Using Energy to Observe Chemical Changes 39 sx07CAGr8_VPhyLab_15.fm Page 40 Thursday, July 19, 2007 9:02 AM Name ___________________________ Date ___________________ Class ____________ 6. Click on the Stockroom to enter. Click the clipboard and select Preset Experiment #8: Heat of Solution NaAc. Click Return to Lab. Repeat the experiment with sodium acetate, NaCH3COO (NaAc). Record the initial and final temperatures in the table. Click the red disposal bucket to clear the lab. Mixture Initial Temperature T1 (ºC) Final Temperature T2 (ºC) NaCl(s) + H2O (l) NaNO3(s) + H2O (l) NaCH3COO(s) + H2O (l) Analyze and Conclude 1. Calculating Find the change in temperature for each mixture. Change in Temperature = T2 T1 __________________________________________________________________ 3. Classifying Which solution(s) had little or no change in temperature ( 0.30°C)? __________________________________________________________________ 4. Applying Concepts When sodium chloride dissolves in water, the ions dissociate or break apart in solution. NaCl(s) → Na+(aq) + Cl–(aq) Write ionic equations, similar to the one above, that describe how NaNO 3 and NaCH3COO dissociate as they dissolve in water. Include heat as a reactant on the left side of the equation or as a product on the right side of the equation. 40 Using Energy to Observe Chemical Changes © Pearson Education, Inc. All rights reserved. Using Energy to Observe Chemical Changes 2. Classifying An exothermic process gives off heat. The reaction mixture warms up and the sign of the change in temperature is positive. An endothermic process absorbs heat. The reaction mixture cools off and the sign of the change in temperature is negative. Which solution(s) are endothermic and which are exothermic? __________________________________________________________________ sx07CAGr8_VPhyLab_16.fm Page 41 Wednesday, August 8, 2007 2:49 PM Name ___________________________ Date ___________________ Class ____________ Lab 16: Boiling Point Elevation Purpose To find out how the boiling point of water changes when a substance is dissolved in it Background Pure water boils at 100°C when the pressure of the atmosphere is 101.3 kPa or 760 torr. But if you dissolve a substance such as table salt (NaCl) in water, the boiling point of the solution is higher than 100°C. This difference is called boiling point elevation. In this assignment, you will dissolve a sample of NaCl in water and measure the boiling point elevation for the solution. Skills Focus Calculating, relating cause and effect, predicting, controlling variables, drawing conclusions Procedure 1. Start Virtual Physical Science. Select Boiling Point Elevation from the list of assignments. The lab will open in the Calorimetry laboratory. A calorimeter is on the lab bench. A sample of sodium chloride (NaCl) is on the balance. Record the mass in Table 1. 3. Continue to observe the temperature until the first appearance of steam comes from the calorimeter. Immediately click the red light on the heater to turn it off and quickly note the temperature. Record the temperature as the boiling point of pure water in Table 1. Letting the water continue to boil will decrease the mass of the water present in the calorimeter. Note that the boiling point may not be exactly 100°C if the atmospheric pressure is not 760 torr. (Torr is a unit of pressure often used by chemists. Normal atmospheric pressure at sea level is 760 torr. 760 torr = 101.3 kPa.) The current atmospheric pressure can be checked by selecting Pressure on the LED meter on the wall. Boiling Point Elevation Boiling Point Elevation © Pearson Education, Inc. All rights reserved. 2. The calorimeter already contains 100 cm3 of water. Make certain the stirrer is On. You should be able to see the shaft rotating. Click on the green heater light on the control panel to turn on the heater and begin heating the water. Click the clock on the wall labeled Accelerate to accelerate the laboratory time. The temperature is displayed in the thermometer window on the left. Observe the temperature closely. Click the clock to turn off time acceleration at approximately 90°C. 41 sx07CAGr8_VPhyLab_16.fm Page 42 Thursday, July 19, 2007 9:02 AM Name ___________________________ Date ___________________ Class ____________ 4. Drag the weighing paper from the balance to the calorimeter and add the NaCl. Wait 30 seconds for the salt to dissolve and then turn on the heater. When steam first appears, observe and record the temperature in Table 1. Table 1 Mass of NaCl (g) Boiling temperature of pure water (ºC) Boiling temperature of solution (ºC) Change in boiling temperature (ºC) Analyze and Conclude 1. What happened to the boiling temperature when the NaCl was added to the water? __________________________________________________________________ 2. Calculating What is the difference between the boiling temperature of pure water and the boiling temperature of water with dissolved NaCl? Record the difference in Table 1. __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ 4. Predicting What effect do you think an increase in the mass of dissolved NaCl would have on the boiling temperature? __________________________________________________________________ 5. Controlling Variables You will conduct an experiment to determine the answer. What variables should remain constant? __________________________________________________________________ Boiling Point Elevation What is the manipulated variable? __________________________________________________________________ What will be the responding variable? __________________________________________________________________ 6. Click on the red disposal bucket to clear the lab. Click on the Stockroom. Click on the clipboard and select Preset Experiment #2: Boiling Point Elevation – NaCl. 42 Boiling Point Elevation © Pearson Education, Inc. All rights reserved. 3. Relating Cause and Effect On a hot summer day the car that you are riding in stalls. It has overheated because of lack of proper coolant. Explain how radiator coolant works. __________________________________________________________________ sx07CAGr8_VPhyLab_16.fm Page 43 Wednesday, August 8, 2007 2:49 PM Name ___________________________ Date ___________________ Class ____________ 7. A calorimeter and bottle of NaCl are on the table. Click Return to Lab. There will already be a quantity of NaCl on the scale. Record the mass in Table 2. 8. Repeat Steps 2–4 of the procedure above using your new sample mass. Record your data in Table 2. Because you have increased your mass, you will need to wait a little longer for the NaCl to dissolve. The heater will not turn on until all of the salt dissolves. Table 2 Mass of NaCl (g) Boiling temperature of pure water (ºC) Boiling temperature of solution (ºC) Change in boiling temperature (ºC) 9. Drawing Conclusions Compare the boiling point elevation in Table 1 with the boiling point elevation in Table 2. What effect did the increased mass of NaCl have on the boiling point elevation of the solutions? Explain. __________________________________________________________________ __________________________________________________________________ Boiling Point Elevation © Pearson Education, Inc. All rights reserved. __________________________________________________________________ Boiling Point Elevation 43 sx07CAGr8_VPhyLab_17.fm Page 44 Thursday, August 9, 2007 6:56 AM Name ___________________________ Date ___________________ Class ____________ Lab 17: Endothermic vs. Exothermic Endothermic vs. Exothermic Problem To examine how adding different solutes can raise or lower the temperature of a solution Background In virtually all chemical reactions, heat is either absorbed or released. A chemical change that absorbs heat (heat in) is termed endothermic. A chemical change that releases heat is called exothermic (heat out). By measuring temperature changes associated with chemical reactions, a process can be identified as an endothermic or exothermic change. In this assignment, you will dissolve several salts in water, measure the resulting temperature change, and then make deductions about the nature of the process. Skills Focus Measuring, classifying, applying concepts Procedure 1. Start Virtual Physical Science and select Endothermic vs. Exothermic from the list of assignments. The lab will open in the Calorimetry laboratory. 2. A bottle of sodium chloride (NaCl) is visible on the lab bench. A weigh paper is on the balance with approximately 2g of NaCl on the paper. A calorimeter containing 100 mL water is on the lab bench. 4. Drag the weigh paper with the sample to the calorimeter until it snaps into place above the calorimeter and then release to pour the sample into the calorimeter. Observe the change in temperature until it reaches a maximum and then record data for an additional 20–30 seconds. Click Stop. (You can click on the clock on the wall labeled Accelerate to accelerate the time in the laboratory.) A blue data link will appear in the lab book. Click the data link and record the temperature before adding the NaCl and the highest or lowest temperature after adding the NaCl in the data table. 5. Click the red disposal bucket to clear the lab. Click on the Stockroom to enter. Click on the clipboard and select Preset Experiment #7: Heat of Soution—NaNO3 and repeat the experiment with NaNO3. Record the initial and final temperatures in the data table. 44 Endothermic vs. Exothermic © Pearson Education, Inc. All rights reserved. 3. Click the Lab Book to open it. Make certain the stirrer is On (you should be able to see the shaft rotating). In the thermometer window, click Save to begin recording data. Allow 20–30 seconds to obtain a baseline temperature of the water. sx07CAGr8_VPhyLab_17.fm Page 45 Thursday, August 9, 2007 6:57 AM Name ___________________________ Date ___________________ Class ____________ 6. Click the red disposal bucket to clear the lab. Click on the Stockroom to enter. Click the clipboard and select Preset Experiment #8: Heat of Solution—NaAc and repeat the experiment with NaCH3COO (NaAc). Record the initial and final temperatures in the data table. Endothermic vs. Exothermic 7. Click the red disposal bucket to clear the lab. Click on the Stockroom to enter. Click the clipboard and select Preset Experiment #6: Heat of Solution— NaOH and repeat the experiment with NaOH. Record the initial and final temperatures in the data table. Data Table T1 T2 T(T2 T1) Exothermic or Endothermic? NaCl (s) + H2O (l) NaNO3 (s) + H2O (l) NaCH3COO (s)+ H2O (l) NaOH (s) + H2O (l) Use your experimental data to answer the following questions. 8. Calculate T (T T2 T1) for each mixture and record it in the data table. © Pearson Education, Inc. All rights reserved. 9. Classifying An exothermic process gives off heat (warms up). An endothermic process absorbs heat (cools off). Which solutions are endothermic and which are exothermic? Record in the data table. 10. Applying Concepts NaCl, commonly known as salt, is often sprinkled on icy roads and sidewalks to melt the ice. From what you have observed in this lab, explain why this is done? (Hint: This process is called freezing point lowering.) __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ Endothermic vs. Exothermic 45 sx07CAGr8_VPhyLab_17.fm Page 46 Thursday, August 9, 2007 6:57 AM Endothermic vs. Exothermic Name ___________________________ Date ___________________ Class ____________ 11. Applying Concepts NaOH is commonly used in drain cleaning products to clean out drains because the heat generated can help dissolve the clogs. What other common endothermic or exothermic chemical products can you think of? __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ © Pearson Education, Inc. All rights reserved. 46 Endothermic vs. Exothermic sx07CAGr8_VPhyLab_18.fm Page 47 Thursday, August 9, 2007 6:58 AM Name ___________________________ Date ___________________ Class ____________ Lab 18: Acid–Base Reactions Purpose To study a neutralization reaction and the role that pH and indicator color play in a titration Background A reaction between an acid and a base is called a neutralization reaction. The acid solution before the reaction has a low pH. The base solution before the reaction has a high pH. When acid and base solutions of equal concentration are mixed in equal amounts, they neutralize each other. The resulting solution has a pH of 7 or close to 7. A neutralization reaction is a double replacement reaction. The products formed are water and a salt. A titration is a process used by chemists to determine the concentration of acid or base in a sample. Acid–Base Reactions Skills Focus Observing, relating cause and effect, applying concepts, interpreting graphs Procedure © Pearson Education, Inc. All rights reserved. 1. Start Virtual Physical Science. Select Acid–Base Reactions from the list of assignments. The lab will open in the Titrations laboratory. 2. Click the Lab Book to open it. The buret (long, glass measuring tube) is filled with NaOH. The beaker contains 25.00 cm3 of HCl with a small amount of bromocresol green as an indicator. The horizontal position of the orange handle is the off position for the buret valve. Open the buret valve by pulling down on the orange handle. The vertical position delivers solution the fastest. There are three intermediate rates in between. Turn the orange handle to one of the faster positions. Observe the titration curve in the Plot window. Also observe the color of the solution in the beaker and carefully note in the Buret Zoom View the volume of NaOH at which the solution changes color. When the volume reaches 35 cm3, double-click the orange handle to stop the titration. Click Save in the Plot window. A blue data link will be created in the lab book. Click on it to view the titration graph. If you need to repeat the titration, click in the Stockroom to enter. Click on the clipboard, and select Preset Experiment #1: Strong Acid–Strong Base. If you do this, the graph will contain a blue line and an additional red line. Disregard the red line. Acid–Base Reactions 47 sx07CAGr8_VPhyLab_18.fm Page 48 Thursday, July 19, 2007 9:10 AM Name ___________________________ Date ___________________ Class ____________ Analyze and Conclude 1. Observing What was the color of the solution in the beaker at the beginning of the titration? __________________________________________________________________ What was the color of the solution in the beaker at the end of the titration? __________________________________________________________________ 2. Observing At about what volume of NaOH did the color change from yellow to blue? (You may need to repeat the experiment and observe the Buret Zoom View.) __________________________________________________________________ Acid–Base Reactions 3. Relating Cause and Effect What occurred in the graph of pH vs. volume at this volume? __________________________________________________________________ What occurred during the titration that would cause the color of the indicator to change? __________________________________________________________________ __________________________________________________________________ 4. Applying Concepts The chemical reaction between hydrochloric acid (HCl) and sodium hydroxide base (NaOH) is both a neutralization and a double replacement reaction. Write a balanced chemical equation to represent the chemical reaction you observed. __________________________________________________________________ What makes NaOH a base? __________________________________________________________________ When the neutralization reaction is complete, what has become of the hydrogen and hydroxide ions? __________________________________________________________________ Because water is neutral, what causes the neutralization of an acid and a base? __________________________________________________________________ 6. What is the salt formed in this neutralization reaction? __________________________________________________________________ 48 Acid–Base Reactions © Pearson Education, Inc. All rights reserved. 5. Relating Cause and Effect What makes HCl an acid? __________________________________________________________________ sx07CAGr8_VPhyLab_18.fm Page 49 Thursday, July 19, 2007 9:10 AM Name ___________________________ Date ___________________ Class ____________ 7. Examine the graph of pH vs. volume (blue line) and sketch the titration curve below. Acid–Base Reactions © Pearson Education, Inc. All rights reserved. 8. Interpreting Graphs What is the pH when the volume of added NaOH is 25.00 cm3? __________________________________________________________________ Acid–Base Reactions 49 sx07CAGr8_VPhyLab_19.fm Page 50 Thursday, August 9, 2007 6:59 AM Name ___________________________ Date ___________________ Class ____________ Lab 19: Energy of a Chemical Reaction Purpose To discover how energy changes during a chemical reaction Background Energy changes occur in all chemical reactions. Some reactions absorb energy, which means that energy must be added to cause the reaction to occur. Chemical reactions that absorb energy are known as endothermic reactions. Cooking food is an endothermic reaction. Other reactions release energy. These are called exothermic reactions. A campfire is an example of an exothermic reaction. Chemists measure the energy released in a chemical reaction using a bomb calorimeter. In a bomb calorimeter a sample is burned in a constant-volume chamber in the presence of oxygen at high pressure. The constant-volume chamber, or bomb, is surrounded by a measured amount of water. The heat released by the reaction in the bomb warms the water that surrounds it. In this experiment, you will combust (or burn in oxygen) a sample of chicken fat. Skills Focus Interpreting graphs, calculating, interpreting data, drawing conclusions Procedure Energy of a Chemical Reaction 2. Click on the Lab Book to open it. 3. Some of the parts of the calorimeter will be identified when the cursor moves over them. To assemble the calorimeter, double-click the following items in numerical order: (1) the cup of chicken fat on the balance pan, (2) the bomb head, (3) the screw cap, and (4) the bomb. Click the calorimeter lid to close it. Combustion experiments can take a long time. Click the clock on the wall labeled Accelerate to accelerate the laboratory time. 4. Click the Bomb Control Panel and the Plot window to bring them to the front. If the Plot window has been closed, click the Graph button on the Bomb Control Panel. Click the Save button on the Bomb Control Panel to save data to the lab book. Allow the graph to proceed for 20–30 seconds to establish a baseline temperature. 5. Click Ignite and observe the graph. Observe the time in the Plot window. When 4.5 minutes have passed, click the Save button in the Plot window to save the graph. A blue link will appear in the lab book. Click the blue link to open the saved graph window. 50 Energy of a Chemical Reaction © Pearson Education, Inc. All rights reserved. 1. Start Virtual Physical Science and select Energy of a Chemical Reaction from the list of assignments. The lab will open in the Calorimetry laboratory. A disassembled bomb calorimeter is visible. A sample of chicken fat is in the calorimeter cup on the balance. The balance has already been tared. sx07CAGr8_VPhyLab_19.fm Page 51 Thursday, July 19, 2007 9:11 AM Name ___________________________ Date ___________________ Class ____________ Analyze and Conclude Use the graph in the Lab Book Plot window to answer the following questions. 1. Interpreting Graphs What was the temperature before igniting the reaction? __________________________________________________________________ What was the temperature after 2 minutes? __________________________________________________________________ At what time was the temperature 26.50 °C? __________________________________________________________________ 2. Calculating By how many degrees did the temperature change from the beginning of ignition until the time that the blue plot line ends? __________________________________________________________________ 3. Interpreting Data Is the combustion of chicken fat endothermic or exothermic? Explain. __________________________________________________________________ __________________________________________________________________ 4. Drawing Conclusions Suppose that in another reaction, the temperature in the bomb calorimeter decreased. What kind of reaction would have occurred? Explain. __________________________________________________________________ __________________________________________________________________ © Pearson Education, Inc. All rights reserved. Energy of a Chemical Reaction Energy of a Chemical Reaction 51 sx07CAGr8_VPhyLab_20.fm Page 52 Thursday, August 9, 2007 7:03 AM Name ___________________________ Date ___________________ Class ____________ Lab 20: Investigating the Properties of Alpha and Beta Particles Problem To investigate the differences in charge and mass of alpha and beta particles Background As scientists began investigating the properties of atoms, they first discovered that negatively charged particles could be extracted. Scientists called these particles electrons. In the context of nuclear decay, however, electrons are known as beta particles. Another particle ejected during nuclear decay is the alpha particle. An alpha particle is a helium nucleus, or a helium atom without its two electrons. Consequently, an alpha particle is positively charged. Ernest Rutherford used alpha particles in his Gold Foil Experiment. Skills Focus Observing, drawing conclusions Procedure 1. Start Virtual Physical Science. Select Investigating the Properties of Alpha and Beta Particles from the list of assignments. The lab will open in the Quantum laboratory. 2. Observing What source is used in this experiment? Drag your cursor over the source to identify it. What detector is used in this experiment? __________________________________________________________________ 3. Turn on the Phosphor Screen. (Click on the green/red button.) What do you observe? __________________________________________________________________ Investigating the Properties of Alpha and Beta Particles The phosphor screen detects charged particles (such as electrons) and it glows momentarily at the positions where the particles impact the screen. __________________________________________________________________ 4. Drag the lab window down and left and the phosphor screen window up and right in order to minimize the overlap. Push the Grid button on the phosphor screen, and set the Magnetic Field to 30 µT. (Click the button above the tens place three times. If you mistakenly click between digits, it will move the decimal point. Click it to place it where it was originally and then click above the tens place.) What happens to the spot from the electron gun on the phosphor screen? __________________________________________________________________ 52 Investigating the Properties of Alpha and Beta Particles © Pearson Education, Inc. All rights reserved. What type of charge do electrons have? __________________________________________________________________ sx07CAGr8_VPhyLab_20.fm Page 53 Thursday, August 9, 2007 7:02 AM Name ___________________________ Date ___________________ Class ____________ 5. Click once above the tens place on the Electric Field meter. Observe the spot. Click a second time above the tens place on the Electric Field. What happens to the spot from the electron gun on the phosphor screen? __________________________________________________________________ 6. Zero out the Magnetic Field and Electric Field meters by clicking on the appropriate digit buttons until the spot on the phosphor screen is centered again. 7. Double-click or click and drag the electron gun to move it to the Stockroom counter. Enter the Stockroom by clicking inside the Stockroom. Double-click the electron gun to move it back to the shelf. Double-click on the alpha source to select it and move it to the Stockroom counter. Click on the green Return to Lab arrow to return to the lab. Drag the alpha source from the Stockroom counter and place it on the table where the electron gun was originally placed (the middle spot light). Click on the front of the alpha source to open the shutter. What appears on the phosphor screen? __________________________________________________________________ 8. Change the unit for the Magnetic Field from µT to mT by clicking once above the unit. Click above the hundreds place three times to set the Magnetic Field to 300 mT (millitesla). This magnetic field is one million times stronger than what we used for the electron gun. Which direction is the spot deflected when the magnetic field is increased this time? __________________________________________________________________ 9. Change the unit for the Electric Field from V to kV by clicking once above the unit. Observe the spot as you increase the Electric Field strength from 0 kV to 5 kV. The movement is slight so pay careful attention. How does this compare with the direction of movement for the electron beam in the Electric Field? __________________________________________________________________ Drawing Conclusions Why does it take significantly stronger magnetic and electric field strengths to move the beam of alpha particles compared with the beam of electrons (beta particles)? __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ Investigating the Properties of Alpha and Beta Particles 53 Investigating the Properties of Alpha and Beta Particles © Pearson Education, Inc. All rights reserved. How does this compare with the direction of movement when the magnetic field was turned on for the electrons? __________________________________________________________________ sx07CAGr8_VPhyLab_21.fm Page 54 Thursday, July 19, 2007 9:12 AM Name ___________________________ Date ___________________ Class ____________ Lab 21: Measuring Speed Measuring Speed Purpose To calculate the speed of an object from measurements of distance and time Background How long does it take you to get to school in the morning? How long will it take you to run a mile? These times depend on the average speed you can travel. Speed is calculated from measurements of distance and time. In this assignment, you will learn the relationship between distance and time for moving objects. Then you will know how to calculate the average speed of anything that moves. Skills Focus Graphing, predicting, interpreting data, applying concepts Procedure 1. Start Virtual Physical Science. Select Measuring Speed from the list of assignments. The lab will open in the Mechanics laboratory. 2. The laboratory is set up with a ball on a table. Attached to the ball is a plunger used to hit the ball. You are going to measure the length of the table and the time it takes the ball to roll across this distance. You will also record the force you used to hit the ball and get it rolling. __________________________________________________________________ __________________________________________________________________ 3. The plunger is initially set to hit the ball with a force of 100 N. Measure the distance (in centimeters) that the ball rolls on the table. Record this length in Table 1. Start the ball rolling by clicking the Force button. When the ball hits the edge of the screen, the experiment will stop. Record in Table 1 the time it took the ball to roll across the table. You will find this time in the Time display on the experiment screen. Repeat the experiment six times using different force settings for the plunger. Click the Reset button. Change the plunger force using the Parameters Palette. You can open the Palette by clicking the Parameters button. In the Palette, click on the Forces tab to change the force settings. Use some weaker and stronger forces. Record your data in Table 1. 54 Measuring Speed © Pearson Education, Inc. All rights reserved. One ball rolls across the full length of a table in a short time. Another ball takes a long time to roll across the same table. How do the speeds of the two balls compare? __________________________________________________________________ sx07CAGr8_VPhyLab_21.fm Page 55 Thursday, August 9, 2007 7:04 AM Name ___________________________ Date ___________________ Class ____________ Table 1 Force (N) Distance of Roll (cm) Time of Roll (s) Measuring Speed Analyze and Conclude © Pearson Education, Inc. All rights reserved. 1. Graphing Plot the time and distance for the initial experiment on the graph. Label the horizontal axis Time (s). Label the vertical axis Distance (cm).You have two data points. The first data point will be (0 s, 0 cm). This is the time and place the roll began. The second data point is the time and distance you measured. You will need to scale the graph to fit your data. 2. On the same graph, plot a different line starting at point (0 s, 0 cm) for each of the different forces you used. The second data point for each line is the time and distance you measured and recorded in Table 1. You might use a different colored pencil for each line. The lines you draw show that the ball started in the same place and traveled the measured distance over a different amount of time. Measuring Speed 55 sx07CAGr8_VPhyLab_21.fm Page 56 Thursday, August 9, 2007 7:05 AM Measuring Speed Name ___________________________ Date ___________________ Class ____________ 3. Each line should have a different steepness. This is called the slope of the line. What does the slope of each line tell you about the ball as it rolled across the table? Think back to what you observed in the different experiments. __________________________________________________________________ Predicting What would you predict for the slope of the line if another ball took an even shorter amount of time to cross the table? __________________________________________________________________ Predicting What would you predict for the slope of the line if another ball took an even longer time to cross the table? __________________________________________________________________ 4. Interpreting Data You can calculate the slope of a line by using the following equation. slope = rise/run In this experiment the rise is the distance the ball traveled. The run is the time it took. Since rise is distance and the run is time, the slope = distance/time. Speed tells you how long it took to go a measured distance, so if you go faster, it takes less time. The slope of each line in your graph is the speed of the ball. From the data on the graph or in Table 1, fill in Table 2 below and calculate the speed of the ball. Table 2 Distance (cm) Time (s) Speed (cm/s) © Pearson Education, Inc. All rights reserved. 5. Applying Concepts On a trip, you measure the time it takes you to travel between City A and City B. If you know the distance between the two cities, how would you calculate the average speed of your trip? __________________________________________________________________ __________________________________________________________________ 56 Measuring Speed sx07CAGr8_VPhyLab_22.fm Page 57 Thursday, August 9, 2007 7:06 AM Name ___________________________ Date ___________________ Class ____________ Lab 22: Graphing Motion Purpose To learn how to use graphs to describe the motion of objects Background Line graphs are used to describe the motion of an object such as a rolling ball, a moving automobile, or an airplane in flight. In this assignment, you will use graphs to describe the motion of several rolling balls with different masses. By analyzing the graphs, you will better understand the motion of the object. Skills Graphing, predicting, interpreting data, drawing conclusions Procedure Graphing Motion 1. Start Virtual Physical Science. Select Graphing Motion from the list of assignments. The lab will open in the Mechanics laboratory. 2. The laboratory is set up with a 10-kg ball on a table. Attached to the ball is a plunger to be used to hit the ball. You will hit the ball and observe it as it rolls across the table. You will record the position of the ball over a period of time in your electronic lab book. You will use your data to make a line graph of the distance traveled versus time. © Pearson Education, Inc. All rights reserved. 3. Click on the Lab Book to open it. Click on the red Recording button to start recording data. Start the ball rolling by clicking on the Force button and wait until the ball hits the end wall. You should see a link appear in the Lab Book. This contains the position versus time data for the ball as it rolls across the table. 4. Click on the data link in your lab book to view the position of the ball throughout the time of the experiment. Record in the table below the positions of the ball at the indicated times. Click the Reset button. Repeat the experiment with a slightly larger mass, and then a slightly smaller mass. Change the mass using the Objects tab under the Parameters Palette. Mass: Time (sec) Mass: Position (m) Time (sec) Mass: Position (m) Time (sec) 0 0 0 1 1 1 2 2 2 3 3 3 4 4 4 5 5 5 6 6 6 Position (m) Graphing Motion 57 sx07CAGr8_VPhyLab_22.fm Page 58 Thursday, August 9, 2007 7:08 AM Name ___________________________ Date ___________________ Class ____________ Analyze and Conclude Graphing Motion 1. Graphing Use data from the data table to graph the motion of the three balls. Your graph should show the distance the ball traveled versus the time, so time is shown on the horizontal or x-axis and distance is shown on the vertical or y-axis. Label the axes with the variable and its units. Use a different colored pencil to connect the points for each ball. You will need to scale the graph to fit your data. __________________________________________________________________ 3. What is the difference between the three lines you graphed? __________________________________________________________________ __________________________________________________________________ 4. The steepness of the line is called the slope of the line. The slope is how far the data goes up on the y-axis (the rise) divided by how far the data goes out on the x-axis (the run). What do the slopes of the lines tell you about each ball? __________________________________________________________________ __________________________________________________________________ 58 Graphing Motion © Pearson Education, Inc. All rights reserved. 2. Interpreting Graphs What does each point on the graph represent? __________________________________________________________________ sx07CAGr8_VPhyLab_22.fm Page 59 Thursday, July 19, 2007 9:13 AM Name ___________________________ Date ___________________ Class ____________ 5. The graph below shows the motion of a dog. Describe the motion of the dog. __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ Time 80 70 60 40 Graphing Motion Distance 50 30 20 10 0 0 2 4 6 8 10 6. How does the graph show that the dog had different speeds in the first four seconds and the last two seconds? __________________________________________________________________ __________________________________________________________________ © Pearson Education, Inc. All rights reserved. __________________________________________________________________ __________________________________________________________________ Graphing Motion 59 sx07CAGr8_VPhyLab_23.fm Page 60 Thursday, July 19, 2007 9:14 AM Name ___________________________ Date ___________________ Class ____________ Lab 23: Acceleration Problem To study the acceleration of a ball when it is thrown straight up into the air Background You experience acceleration when you walk faster to get somewhere on time, or slow down to talk to a friend, or turn a corner as you walk down the hall. What do these movements have in common? They are examples of a change in speed or a change in direction. A change in the speed or direction of a moving object is acceleration. Acceleration can be positive (speeding up) or negative (slowing down). Negative acceleration is sometimes called deceleration. Skills Focus Predicting, observing, graphing, interpreting data, drawing conclusions Procedure 1. Start Virtual Physical Science. Select Acceleration from the list of assignments. The lab will open in the Mechanics laboratory. 2. The laboratory is set up with a ball near the bottom of the experiment window. A plunger is attached to the bottom of the ball. The ball will be shot straight up into the air by the plunger, but there will be gravity to pull it back down. You will observe the acceleration of the ball as it rises in the air and then falls back to the bottom of the screen. Acceleration __________________________________________________________________ 3. Click on the Lab Book to open it. Click on the red Recording button to start recording data. Hit the ball into the air by clicking on the Force button. Observe the trajectory or path of the ball. The force of the plunger is initially set to hit the ball with a force of 200 newtons (N). When the ball reaches the bottom, the experiment will stop. You should see a link appear in the Lab Book. This contains the position versus time data and the velocity versus time data for the ball flying through the air. If you click on the data link, the Data Viewer window will open with three columns of data. The first column, t (sec), is Time. The second column, y (m), gives the Position of the ball. The third column, v_y (m/s), gives the Velocity. 60 Acceleration © Pearson Education, Inc. All rights reserved. Predicting How will the speed of the ball change as it moves up in the air? How will the speed change as the ball falls back down? __________________________________________________________________ sx07CAGr8_VPhyLab_23.fm Page 61 Thursday, July 19, 2007 9:14 AM Name ___________________________ Date ___________________ Class ____________ 4. Try the experiment again with different forces on the plunger. Click the Reset button to reset the experiment. Click the Parameters button. Change the force in the Parameters Palette to a different value by clicking the Forces tab in the Palette and repeat Step 3. Hit the ball with two different forces. Use larger and smaller forces. Observing In each of these experiments where, along its path, does the ball accelerate? __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ Analyze and Conclude 1. Graphing Use the data in each of the data links in your Lab Book to draw the position versus time graphs on the grid below. Label the horizontal axis Time (s) and the vertical axis Position (m). You will need to scale the graph to fit your data. Use about 10 points from each data link to describe the trajectory of the ball. The first data point in each graph is (0 m, 0 s). This is the time and place where the ball was hit. You will be plotting the height of the ball (the y data) over the time period of the whole trajectory of rising and falling. Use a different colored pencil for each experiment. Connect the data points with lines. Note: Ignore all data in which the ball’s position is negative. © Pearson Education, Inc. All rights reserved. Acceleration Acceleration 61 sx07CAGr8_VPhyLab_23.fm Page 62 Friday, August 10, 2007 12:40 PM Name ___________________________ Date ___________________ Class ____________ 3. Interpreting Data How do the velocity versus time graphs show that the balls are accelerating? __________________________________________________________________ __________________________________________________________________ 4. What does the negative slope of the velocity graph above the horizontal axis mean? What does the negative slope of the velocity graph below the horizontal axis mean? __________________________________________________________________ __________________________________________________________________ 5. Drawing Conclusions Is there a relationship between the slopes of the lines and the plunger forces? Hint: Does the size of the force used to hit the ball have anything to do with the velocity when the ball was falling? What about the velocity when the ball was rising? __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ 62 Acceleration © Pearson Education, Inc. All rights reserved. Acceleration 2. After you have made your graphs of position versus time, select the velocity versus time data from the data link. Graph velocity versus time on the grid below. Label the horizontal axis Time (s) and the vertical axis Velocity (m/s). Use about 10 data points to describe the trajectory of the balls. Connect the points. Use the same colors or line styles for the same experiments as you did for the first graph. Label each line with the plunger force. Identify the parts of the trajectory where the speed is increasing, where the speed is decreasing, and where the ball is changing direction. (Hint: Choose equal amounts between the intervals.) sx07CAGr8_VPhyLab_24.fm Page 63 Thursday, July 19, 2007 9:15 AM Name ___________________________ Date ___________________ Class ____________ Lab 24: Forces Purpose To understand the effects of balanced and unbalanced forces on an object Background Have you ever played tug of war or arm wrestled with a friend? To win, you must use a force greater than that of your opponent. If the force you use is equal to the force of your opponent, the opposing forces are balanced and the net force is zero. Nobody wins. When the net force, or sum of the forces, is not equal to zero, the forces are unbalanced. Unbalanced forces cause objects to move, stop moving, or change direction. You can predict the motion of objects by looking at the net forces acting on them. In this assignment you will watch balls being acted on by forces and determine whether the net force is balanced or unbalanced. Skills Focus Observing, controlling variables, applying concepts Procedure 1. Start Virtual Physical Science. Select Forces from the list of assignments. The lab will open in the Mechanics laboratory. 2. The laboratory is set up with a ball at the top of the experiment window. Attached to the bottom of the ball is a rocket to push (force) the ball up. In this experiment, gravity has been turned on. Gravity will tend to pull the ball down. The object in this experiment is to apply just the right amount of force with the rocket to keep the ball from going up or from falling. Observing What did you observe when you turned on the rocket? __________________________________________________________________ 4. Now experiment to determine the amount of force needed to balance the ball. Click the Reset button to go back to the beginning of the experiment. Use the Forces tab in the Parameters Palette to change the rocket force and repeat Step 3. Observe whether the ball falls or goes up. Record each force you try and your observations in Table 1. Continue until you can keep the ball from either falling or rising. Why do you need to change the rocket’s force? __________________________________________________________________ Forces © Pearson Education, Inc. All rights reserved. 3. Start the experiment by clicking on the Start button. Observe what happens. To turn on the rocket, click on the Force button. When you are done with your observations, click the Pause button to stop the experiment. __________________________________________________________________ Forces 63 sx07CAGr8_VPhyLab_24.fm Page 64 Thursday, July 19, 2007 9:15 AM Name ___________________________ Date ___________________ Class ____________ Table 1 Force (N) Observations Balanced/Unbalanced 5. Controlling Variables Now find out what happens to the motion of the ball when the rocket is attached to the ball at a different position. Reset the experiment to the beginning by clicking on the Reset button. Using the Parameters Palette, set the angle of the rocket to 270°and set the force to 200 N. Record your observations in Table 2. Now repeat the experiment using angles of 0°, 180°, and an angle of your choice. Record your results in Table 2. Table 2 Force (N) 270° 200 0˚ 200 180˚ 200 Effect on the Ball Balanced/Unbalanced 200 Analyze and Conclude 1. What is the difference between the forces used in Table 1 and those in Table 2? __________________________________________________________________ __________________________________________________________________ 2. How do balanced forces affect the ball? __________________________________________________________________ 3. How do unbalanced forces affect the ball? __________________________________________________________________ Forces 4. Applying Concepts Why would it be important to understand the concept of net force when trying to build a rocket to travel to the moon? __________________________________________________________________ __________________________________________________________________ 64 Forces © Pearson Education, Inc. All rights reserved. Angle sx07CAGr8_VPhyLab_25.fm Page 65 Thursday, August 9, 2007 7:33 AM Name ___________________________ Date ___________________ Class ____________ Lab 25: Measuring Friction: A Sticky Topic Measuring Friction: A Sticky Topic Problem To discover how friction affects the motion of a sliding object Background Friction is a force that acts in the opposite direction of motion. A car moves because of the friction between its tires and the ground. Walking is usually easy because your feet slightly stick to the ground or floor. As you walk forward, your foot pushes backwards. Because of friction your feet don’t slide out from under you unless you are on ice. In this lab you will discover the effects of different surfaces and materials on the time it takes for friction to stop a sliding sled. Skills Focus Interpreting data, predicting, drawing conclusions, applying concepts Procedure 1. Start Virtual Physical Science. Select Measuring Friction from the list of assignments. The lab will open in the Mechanics laboratory. 2. The laboratory is set up with a sled, or block, on a table. A plunger is attached to start the sled moving. Notice that the table is made of cement and the sled is made of wood. You will hit the sled and watch it slide across the table. Note that the mass of the sled is 1 kg. What is the weight of the sled in newtons? © Pearson Education, Inc. All rights reserved. Remember Weight = Mass Acceleration due to gravity. __________________________________________________________________ Predicting Would it be easier to push this rubber sled or a metal sled? __________________________________________________________________ __________________________________________________________________ 3. Click on the Lab Book to open it. Click the Record button to start recording data. Start the sled sliding on the table by clicking on the Force button. Observe what happens. The plunger hit the sled with a force of 225 newtons. As soon as the sled stops moving, click the Stop button to stop the experiment. Click the Stop button to stop recording data. You should see a link appear in the lab book. This contains the position versus time data of the sled sliding on the table. Use this data to record in the table below the distance the sled traveled and the time it took the sled to stop. Measuring Friction: A Sticky Topic 65 sx07CAGr8_VPhyLab_25.fm Page 66 Thursday, August 9, 2007 7:33 AM Measuring Friction: A Sticky Topic Name ___________________________ Date ___________________ Class ____________ 4. Try other types of materials for the sled and the table to see how changes in friction affect the sled’s stopping time. Click the Reset button to reset the experiment before trying new materials. Choose different materials in the Parameters Palette under the Frictions tab. The sled’s appearance will not change. For each trial record in the table below the materials of the sled and the table, the distance the sled travels until it stops, and the time it takes to stop. Table Material of the Sled Material of the Table Wood Cement Sliding Distance (m) Sliding Time (s) Analyze and Conclude 2. Interpreting Data With what materials did the sled slide longest? With what materials did the sled stop fastest? Why? __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ 3. Predicting What would happen if you repeated the experiment using a heavier sled? __________________________________________________________________ 4. Drawing Conclusions Describe how the amount of friction between an object and a surface determines the amount of force needed to move the object. __________________________________________________________________ 5. Applying Concepts If you were designing an automobile tire, would you want to have a lot of friction (very sticky and rough), not a lot of friction (very smooth), or somewhere in between? Why? 66 Measuring Friction: A Sticky Topic © Pearson Education, Inc. All rights reserved. 1. What stops the sled from moving? __________________________________________________________________ sx07CAGr8_VPhyLab_26.fm Page 67 Thursday, August 9, 2007 7:34 AM Name ___________________________ Date ___________________ Class ____________ Lab 26: Acceleration and Friction Purpose To investigate the effect that friction has on the acceleration of an object Background Have you ever tried to ride a bike with flat tires, or push a heavy crate across a rough floor? Chances are you couldn’t get the bike or the crate to move very fast. What makes these activities so hard is the large amount of friction involved. In this assignment, you will look at the effect of friction on the acceleration of an object. Skills Focus Graphing, interpreting data, drawing conclusions Acceleration and Friction Procedure 1. Start Virtual Physical Science. Select Acceleration and Friction from the list of assignments. The lab will open in the Mechanics laboratory. 2. The laboratory is set up with a sled on a table. The surface of the table can be covered with different kinds of sandpaper. Attached to the sled is a small rocket that will be used to push the sled. Click on the Lab Book to open it. 3. In the first experiment, the friction coefficient will be set at 0.1. Click on the red Recording button to save the position versus time data. Click on the Force button to start moving the sled. The rocket should turn off automatically after two seconds. When the sled has stopped moving, click on the Pause button to stop the experiment and stop recording data. A new data link should appear in your Lab Book. Click the Reset button to reset the experiment. © Pearson Education, Inc. All rights reserved. 4. Repeat Step 3 five more times using coefficients of friction of 0.2, 0.3, 0.4, 0.5, and 0.6. Use the Frictions tab in the Parameters Palette to change the friction. The table below summarizes the different conditions for the experiments. Table Initial Position (m) Force (N) Coefficient of Friction 0 10 0.1 0 10 0.2 0 10 0.3 0 10 0.4 0 10 0.5 0 10 0.6 Acceleration and Friction 67 sx07CAGr8_VPhyLab_26.fm Page 68 Thursday, July 19, 2007 9:16 AM Name ___________________________ Date ___________________ Class ____________ Analyze and Conclude Acceleration and Friction 1. Graphing On the grids below, graph the position versus time for each of the six different experiments. Graph the first three experiments on the top grid and the other three on the bottom grid. Use the data found in the data links saved in your Lab Book. Label the horizontal axis Time (s). Label the vertical axis Distance (m). Use a different colored pencil for each graph. You will need to scale the graphs to fit your data. © Pearson Education, Inc. All rights reserved. 68 Acceleration and Friction sx07CAGr8_VPhyLab_26.fm Page 69 Thursday, July 19, 2007 9:16 AM Name ___________________________ Date ___________________ Class ____________ 2. Identify on the graphs the place where the rocket finished firing. Do this for each data run. 3. Interpreting Data As the friction increases, what happens to the shape of the position versus time graphs during the firing interval? Explain why. __________________________________________________________________ __________________________________________________________________ 4. What happens to the shapes of the position versus time graphs after the rockets turn off? __________________________________________________________________ 5. How does the frictional force affect the acceleration of the sled? How does the rocket force affect the acceleration of the sled? __________________________________________________________________ © Pearson Education, Inc. All rights reserved. Acceleration and Friction __________________________________________________________________ Acceleration and Friction 69 sx07CAGr8_VPhyLab_27.fm Page 70 Thursday, August 9, 2007 7:36 AM Name ___________________________ Date ___________________ Class ____________ Lab 27: Gravity and Free Fall Motion Purpose To find out what effect air resistance has on a falling object Background When an object falls through the air, two forces act on it. The force of gravity pulls the object down and the force of air resistance slows the object’s fall by opposing the motion. Air resistance is an example of fluid friction, which applies an opposing force through a gas or liquid. When you stick your hand out the window of a moving car, you can feel the air resistance against your hand. As the car goes faster, the air resistance increases. If you have jumped into a pool, you have felt the resistance of water, which slows you down much faster than air does. In this assignment, you will observe the effects of air resistance on the acceleration of falling objects. Skills Focus Graphing, intepreting data, drawing conclusions Procedure 2. The laboratory is set up with a ball at the top of the experiment window, 20 m above the surface. Gravity is set at the same value as on Earth. Gravity will pull the ball down. You will observe how long it takes the ball to reach y = 0. The mass of the ball is 2 kg. The diameter of the ball is 1 m. 3. Click on the Lab Book to open it. Click on the red Recording button to start recording data. Start the experiment by clicking on the Start button and observe what happens. When the ball reaches y = 0, the experiment will stop. You should see a link appear in the Lab Book. This contains the velocity versus time data for the ball falling. In the table on the next page, write the amount of time it took the ball to fall and its velocity at the nearest data point to when the ball crosses y = 0. 4. Click the Reset button to reset the experiment. Place the air resistance graphic from the tray onto the work area. Repeat Step 3 to record the velocity of the ball as it falls. 5. Drop another ball with the same mass as before but a much larger diameter (for example, a large hollow ball). Click the Reset button to reset the experiment. Use the Objects tab in the Parameters Palette to adjust the radius to 4 m. Repeat Step 3. 70 Gravity and Free Fall Motion © Pearson Education, Inc. All rights reserved. Gravity and Free Fall Motion 1. Start Virtual Physical Science. Select Gravity and Free Fall Motion from the list of assignments. The lab will open in the Mechanics laboratory. sx07CAGr8_VPhyLab_27.fm Page 71 Thursday, August 9, 2007 7:36 AM Name ___________________________ Date ___________________ Class ____________ 6. Click the Reset button again. Use the Parameters Palette to adjust the radius to 4 m again, but this time, place the air resistance graphic back on the table from the tray. Repeat Step 3 to record the velocity of the ball as it falls. Mass of Ball (kg) Diameter (m) Air Resistance (on or off?) 2 1 off 2 1 on 2 4 off 2 4 on Time to Reach y 0 (s) Velocity at y 0 (m/s) Analyze and Conclude Gravity and Free Fall Motion © Pearson Education, Inc. All rights reserved. 1. Graphing Using the data in each of the data links in the Lab Book, draw the velocity versus time graphs for each experiment on the grid below. Label the horizontal axis Time (s) and the vertical axis Velocity (m/s). Scale your graph to fit your data. The first data point is (0 s, 0 m/s) for each experiment. Connect the data points using a different colored pencil for each graph. Label each line with the radius of the ball and indicate if there was air resistance. 2. Interpreting Data Describe any differences you see in the graphs. Explain why the graphs are different. Is there a difference in the motion of the objects with or without air resistance? __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ Gravity and Free Fall Motion 71 sx07CAGr8_VPhyLab_27.fm Page 72 Thursday, July 19, 2007 9:16 AM Name ___________________________ Date ___________________ Class ____________ 3. Interpreting Data Why do two of the graphs look exactly the same? __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ 4. Interpreting Data Do the graphs of experiments with air resistance have any regions that show constant acceleration? Do they have any regions with constant velocity, or no acceleration? Why wouldn’t the balls accelerate even with gravity still pulling them down? What is stopping them? __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ 5. Drawing Conclusions The point at which a falling object stops accelerating is called the terminal velocity. Why is terminal velocity an appropriate name? __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ 6. How would the motion of the balls change if you increased the force of gravity with air resistance on? __________________________________________________________________ __________________________________________________________________ 72 Gravity and Free Fall Motion © Pearson Education, Inc. All rights reserved. Gravity and Free Fall Motion Going Further sx07CAGr8_VPhyLab_28.fm Page 73 Thursday, July 19, 2007 9:17 AM Name ___________________________ Date ___________________ Class ____________ Lab 28: Newton’s First Law Purpose To discover how mass and inertia are related Background Motion surrounds you in your everyday life. Scientists have been fascinated by it for thousands of years. Sir Isaac Newton proposed three laws to describe motion. Newton’s first law of motion states that an object at rest will remain at rest, and an object moving at a constant velocity will continue moving at a constant velocity, unless it is acted on by an outside force. This is also called the law of inertia. In this assignment you will measure the distance it takes a force to stop the motion of balls of different masses. The data you collect will provide a measure of the inertia of different objects and their tendency to resist change. Skills Focus Graphing, predicting, interpreting data, drawing conclusions, controlling variables Procedure 1. Start Virtual Physical Science. Select Newton’s First Law from the list of assignments. The lab will open in the Mechanics laboratory. 3. After a couple of seconds, press the Force button to turn on the rocket. The Force is set to 10 N. Click the Pause button when the ball slows down and starts to reverse direction. You should see a link appear in the Lab Book. This contains the position versus time data and the velocity versus time data of the ball rolling across the table. 4. Use the data collected to fill out the table below with (1) the magnitude of the force, (2) the distance the ball traveled from when the force was turned on to when it stopped and reversed direction, and (3) the amount of time the force was on. Find in the data the time when the velocity is decreasing, but is still positive, showing that the ball is still traveling to the right, but the force is acting on the ball. You can find the distance traveled and the time from this part of the data. Newton’s First Law Newton’s First Law © Pearson Education, Inc. All rights reserved. 2. The laboratory is set up with a 2-kg ball on a table. Attached to the ball is a rocket used to push the ball in the direction opposite to the motion of the ball. The ball will have an initial velocity. There is no friction. The only thing stopping the ball is the force you turn on. Click on the Lab Book to open it. Click on the red Recording button to start recording data. Start the ball rolling across the table by clicking on the Start button. 73 sx07CAGr8_VPhyLab_28.fm Page 74 Thursday, July 19, 2007 9:17 AM Name ___________________________ Date ___________________ Class ____________ 5. Controlling Variables Repeat the experiment with balls of three different masses. Remember to click the Reset button before choosing each new mass. Use the Objects tab under the Parameter Palette to change the mass of the ball. Keep the force the same for all of the experiments. The time the rocket is on will be different for each ball, because all the balls will stop in different amounts of time. Table Mass of Ball (kg) Force Applied to Ball (N) Distance Traveled After Rocket Was Turned On (m) Time Rocket Is On (s) Analyze and Conclude Newton’s First Law 74 Newton’s First Law © Pearson Education, Inc. All rights reserved. 1. Graphing On the grid below, graph the distance versus time for each of the four experiments. Use the data in the data links saved in your Lab Book. Label the horizontal axis as Time (s) and the vertical axis as Distance (m). Decide on the proper scaling for the axes. Use a different colored pencil for each graph. Label the point at which the rocket was turned on in each experiment. sx07CAGr8_VPhyLab_28.fm Page 75 Thursday, July 19, 2007 9:17 AM Name ___________________________ Date ___________________ Class ____________ 2. Interpreting Data Which mass was easiest to stop? Which was hardest? How do you know? __________________________________________________________________ __________________________________________________________________ 3. Predicting What would happen if you had a smaller force pushing on the same balls? Would they still stop? Hint: The balls have initial velocity but what is actually making the balls stop? __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ 4. Making Generalizations You have worked with rocket forces in this lab, but what other types of forces do you think would change the motion of the ball? __________________________________________________________________ __________________________________________________________________ 5. Drawing Conclusions What would happen if you increased the mass of the ball but didn’t apply any force? __________________________________________________________________ __________________________________________________________________ What is the relationship between the mass of an object and its inertia or resistance to motion? __________________________________________________________________ Newton’s First Law © Pearson Education, Inc. All rights reserved. __________________________________________________________________ Newton’s First Law 75 sx07CAGr8_VPhyLab_29.fm Page 76 Thursday, July 19, 2007 9:17 AM Name ___________________________ Date ___________________ Class ____________ Lab 29: Newton’s Second Law Newton’s Second Law Purpose To investigate how force and mass affect the acceleration of an object Background Newton’s second law of motion states that the acceleration of an object depends on the object’s mass and the net force applied to the object. The law can be written mathematically as Force Mass Acceleration or F m a. This equation can also be rearranged. Acceleration Force -------------Mass Skills Focus Graphing, predicting, interpreting graphs, controlling variables, drawing conclusions Procedure 1. Start Virtual Physical Science. Select Newton’s Second Law from the list of assignments. The lab will open in the Mechanics laboratory. Predicting What do you think your velocity versus time graphs will look like if the ball is accelerating? __________________________________________________________________ 3. Click on the Lab Book to open it. Click on the red Recording button to start recording data. Start the ball rolling by clicking on the Force button. Observe what happens as the ball rolls across the table. The force is set to 10 N and the mass of the ball is 1 kg. Does the ball speed up? The ball will stop when it reaches the end of the table. You should see a link appear in the Lab Book containing the position versus time and velocity versus time data of the ball rolling across the table. 4. Click the Reset button to reset the experiment back to the beginning. Use the Forces tab under the Parameters Palette to change the rocket force and repeat Step 3 for two different forces. Record the forces in the table below. 76 Newton’s Second Law © Pearson Education, Inc. All rights reserved. 2. The laboratory is set up with a ball on a table. Attached to the ball is a rocket used to push the ball across the table. There is no friction. In this experiment, you will collect position and velocity data as the ball moves across the table. Then you will make position and velocity graphs. sx07CAGr8_VPhyLab_29.fm Page 77 Thursday, July 19, 2007 9:17 AM Name ___________________________ Date ___________________ Class ____________ Newton’s Second Law 5. Now observe what happens to the ball’s speed and acceleration when you change the mass. Click the Reset button to reset the experiment back to the beginning. Use the Objects tab under the Parameters Palette to change the mass of the ball. Make sure the force is set to 10 N, and repeat Step 3 for two different masses. Don’t change the force for these experiments. Record the masses in the table. Table Force (N) Mass of Ball (kg) 10 1 Color of Line on Graph 1 1 10 10 Analyze and Conclude © Pearson Education, Inc. All rights reserved. 1. Graphing Using the data in each of the data links in your Lab Book, draw the position versus time graphs on the grid below. You will be plotting the distance of the ball versus the time as the ball crossed the table. Label the horizontal axis as Time (s) and the vertical axis as Distance (m). Choose a scale for your graph that fits your data. The first data point will be (0 s, 0 cm). This is the time and position of the ball when it started rolling. Plot ten points for each ball. Connect the data points using a different colored pencil for each experiment. In the table above, write down the color of the line you draw for each set of data. Newton’s Second Law 77 sx07CAGr8_VPhyLab_29.fm Page 78 Thursday, July 19, 2007 9:17 AM Newton’s Second Law Name ___________________________ Date ___________________ Class ____________ 2. Now select the velocity versus time data from your data links and graph velocity versus time on the grid below. Label the horizontal axis Time (s) and the vertical axis Velocity (m/s). Label each line with the force and mass of the ball. Use the same colors for the graphs with the same masses and forces. __________________________________________________________________ How do the velocity versus time graphs show that the balls are accelerating? __________________________________________________________________ __________________________________________________________________ Which ball accelerated the most? __________________________________________________________________ 4. Controlling Variables Explain how you could produce a large acceleration using a very small force. __________________________________________________________________ 5. Drawing Conclusions What are two ways in which you can increase acceleration? __________________________________________________________________ 78 Newton’s Second Law © Pearson Education, Inc. All rights reserved. 3. Interpreting Graphs How do the position versus time graphs show that the balls are accelerating? __________________________________________________________________ sx07CAGr8_VPhyLab_30.fm Page 79 Thursday, July 19, 2007 9:18 AM Name ___________________________ Date ___________________ Class ____________ Lab 30: Newton’s Third Law Purpose To study action and reaction by observing collisions between moving balls Background In the past, cannons were an important weapon for reaching the enemy at a distance. However, soldiers had to be careful not to stand behind a cannon when it was fired. The heavy cannon would “kick” back or roll backward with each shot. This “kick” back is an example of Newton’s third law of motion: For every action (the cannon ball firing forward at high speed) there is an equal and opposite reaction (the cannon moving backwards at low speed). In this assignment, you will observe the effects of reaction forces when balls of different masses collide. Skills Focus Newton’s Third Law Predicting, interpreting data, applying concepts, drawing conclusions Procedure 1. Start Virtual Physical Science. Select Newton’s Third Law from the list of assignments. The lab will open in the Mechanics laboratory. 2. The laboratory is set up with two balls of the same mass on a table. The balls will move towards each other. As they collide they will exert forces on each other which are equal and opposite. Predicting When a more massive ball hits a less massive ball, how do the forces they exert on each other compare? What is the resulting motion of the balls? __________________________________________________________________ __________________________________________________________________ © Pearson Education, Inc. All rights reserved. __________________________________________________________________ 3. The initial velocity of all of the balls will be the same for each trial, but the masses of the balls will change. You will observe what happens in the collisions and record the final velocities of each ball. 4. Click the Start button to start the balls in motion. After the balls bounce off each other and move a short distance away from each other, click the Pause button to stop the experiment. Note the velocity of each ball in the display panel below the table. The display panel is set to show the values for Ball 1. You can switch the values to Ball 2 by clicking on the arrows below Tracking on the lower right. Record the velocities in the table. Describe what happened to each ball in the reaction box. 5. Click the Reset button to reset the experiment before trying new masses. Use the table to keep track of what mass to use for each trial. Use the Objects tab under the Parameters Palette to change the mass of the balls. Make sure to Newton’s Third Law 79 sx07CAGr8_VPhyLab_30.fm Page 80 Thursday, July 19, 2007 9:18 AM Name ___________________________ Date ___________________ Class ____________ uncheck the box that reads “Balls Same Mass and Diameter” so you can try balls of different masses. Set a negative velocity (moving to the left) by adjusting the angle of the velocity to 180 degrees. Table Velocity Before Trial 1 Mass (kg) Ball 1 10 10 Ball 2 10 10 Ball 1 20 10 Ball 2 10 10 Ball 1 50 10 Ball 2 1 10 Ball 1 1 10 Ball 2 50 10 Velocity After Reaction Trial 2 Newton’s Third Law Trial 3 Trial 4 Analyze and Conclude __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ 2. Applying Concepts Explain why a lighter ball has more velocity after a collision with a heavy ball than it had before. Where did that velocity come from? Hint: Think about Newton’s second law. __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ 3. Drawing Conclusions Does the data prove your earlier prediction? Explain. __________________________________________________________________ 4. Drawing Conclusions Why don’t the forces of action and reaction cancel each other? Why isn’t the net force zero if the forces are the same in each direction? __________________________________________________________________ 80 Newton’s Third Law © Pearson Education, Inc. All rights reserved. 1. Interpreting Data Describe what happened when the masses of the balls were the same, and when they were very different. __________________________________________________________________ sx07CAGr8_VPhyLab_31.fm Page 81 Friday, August 17, 2007 6:56 AM Name ___________________________ Date ___________________ Class ____________ Lab 31: Conservation of Momentum Purpose To discover what happens to the total momentum when objects collide Background You might think of conservation as paying attention to how much water or gas you use. But conservation also means that conditions before and after an event do not change. Conservation of momentum means that the total momentum of any group of objects before an event is the same as it is afterwards. No momentum has been lost and none has been gained. In this assignment you will observe a system of two balls colliding. You will measure the momentum before and after the collision and see if the two measurements are the same. Skills Focus Interpreting data, drawing conclusions, applying concepts Procedure 1. Start Virtual Physical Science. Select Conservation of Momentum from the list of assignments. The lab will open in the Mechanics laboratory. 2. The laboratory is set up with two balls of the same mass on a table. You will perform three experiments to measure the momentum of the system by measuring the momentum of each ball within the system. © Pearson Education, Inc. All rights reserved. Conservation of Momentum 3. Experiment 1: Two balls moving The masses of the balls are the same. The velocities of the balls are the also the same in magnitude (size) but they are not the same in direction. (The balls will be heading towards each other.) The balls start out separated by 10 meters. Click the Start button to watch them collide. Click the Pause button immediately after they bounce off each other. Record the final velocity of each ball in Table 1 using the data in the display panel in the experiment window. You will need to click the arrows under Tracking to change the values in the panel from Ball 1 to Ball 2. Table 1 Trial 1 Mass (kg) Velocity Before (m/s) Ball 1 10 –10 Ball 2 10 10 Velocity After (m/s) Momentum Before (mass x velocitybefore) Momentum After (mass x velocityafter) Total Momentum = Conservation of Momentum 81 sx07CAGr8_VPhyLab_31.fm Page 82 Friday, August 10, 2007 12:41 PM Name ___________________________ Date ___________________ Class ____________ 4. Experiment 2: One ball moving Click the Reset button to reset the experiment. Use the Objects tab under the Parameters Palette to change the mass of Ball 1 to 15 kg and the mass of Ball 2 to 5 kg. (First uncheck “Balls Same Mass and Diameter.”) Set the velocity of Ball 1 to –10 m/s and the velocity of Ball 2 to 0 m/s. Set a negative velocity (moving to the left) by adjusting the angle of the velocity to 180 degrees. Click the Start button to watch the balls collide. Click the Pause button immediately after they bounce off each other and before ball 2 hits the wall. Record the final velocity of each ball in Table 2 using the data in the display panel in the experiment window. Table 2 Trial 2 Mass (kg) Velocity Before (m/s) Ball 1 15 –10 Ball 2 10 0 Velocity After (m/s) Momentum Before (mass x velocitybefore) Momentum After (mass x velocityafter) Total Momentum = 5. Experiment 3: Choose your own variables Click the Reset button to reset the experiment. Choose your own masses and velocities for each ball. Then predict what you think the resulting velocities might be after the collision. Test your prediction. Record the data in Table 3. Trial 3 Mass (kg) Velocity Before (m/s) Prediction: Velocity After (m/s) Actual: Velocity After (m/s) Ball 1 Ball 2 Total Momentum = 82 Conservation of Momentum Momentum Before (mass x velocitybefore) Momentum After (mass x velocityafter) © Pearson Education, Inc. All rights reserved. Conservation of Momentum Table 3 sx07CAGr8_VPhyLab_31.fm Page 83 Thursday, August 9, 2007 7:38 AM Name ___________________________ Date ___________________ Class ____________ Analyze and Conclude 1. Interpreting Data Is the momentum of the system conserved in each trial? Explain. __________________________________________________________________ __________________________________________________________________ 2. Applying Concepts If the balls were initially traveling along the same line and in the same direction, would they also obey the law of conservation of momentum? Try it out with Ball 1 going twice as fast as Ball 2 but both heading to the right with some positive velocity. In the Parameters Palette, set the angle of the velocity to be the same for both balls (Angle of 0°). Was there anything that surprised you about this collision? __________________________________________________________________ __________________________________________________________________ 3. Drawing Conclusions How can a ball with a small mass have the same momentum as a ball with a large mass? __________________________________________________________________ 4. Describe momentum in your own words. __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ © Pearson Education, Inc. All rights reserved. Conservation of Momentum Conservation of Momentum 83 sx07CAGr8_VPhyLab_32.fm Page 84 Thursday, August 9, 2007 7:42 AM Name ___________________________ Date ___________________ Class ____________ Lab 32: Floating Objects Purpose To determine the buoyant force Background Water and other fluids exert an upward force called the buoyant force that acts on a submerged object. The buoyant force acts in the direction opposite to the force of gravity, so it makes an object feel lighter. All objects take up space. A submerged object displaces, or takes the place of, a volume of fluid equal to its own volume. Archimedes, a mathematician of ancient Greece, discovered a connection between the weight of a fluid displaced by an object and the buoyant force acting on it. Archimedes’ principle states that the buoyant force acting on a submerged object is equal to the weight of the fluid the object displaces. Skills Focus Calculating, problem solving, drawing conclusions, and relating cause and effect Procedure 1. Start Virtual Physical Science. Select Floating Objects from the list of assignments. The lab will open in the Density laboratory. Determining Density 3. Click on the graduated cylinder to see a zoomed-in view of the level of the fluid. Record the initial volume of the fluid in Table 1. Place the beaker on the counter next to the cylinders on the balance and record the mass in Table 1. Drag the beaker back to the spotlight on the counter. Floating Objects 4. Drag the cylinder to the beaker and empty the Virtual Fluid into the beaker. Place the beaker on the balance and record the mass in Table 1. Drag the beaker back to the cylinder to pour the fluid back in. Release when the beaker snaps into place over the top of the cylinder. 84 Floating Objects © Pearson Education, Inc. All rights reserved. 2. Use the Up and Down arrows on the control panel to toggle through the options of fluids to use in the lab. Select the Virtual Fluid C. Click the Full button underneath that display to select the amount of fluid to be added to the cylinder. Click the Fill button to release the chosen amount of fluid into the cylinder. sx07CAGr8_VPhyLab_32.fm Page 85 Thursday, August 9, 2007 7:42 AM Name ___________________________ Date ___________________ Class ____________ Table 1 Volume of Virtual Fluid (mL) Mass of beaker only (g) Mass of beaker and Virtual Fluid (g) Determining Buoyant Force 5. Click on the cylinder to zoom in to record the volume again in Table 2. 6. Find the steel ball on the lab wall. Pick up the ball and drag it to the spotlight on the balance. Record the mass in Table 2. 7. Drag the steel ball to the top of the cylinder and release it there. The ball remains suspended above the fluid until you click the green Drop button, which allows the ball to fall into the fluid. Click on the cylinder and record the volume in Table 2. Table 2 Volume of Virtual Fluid only (mL) Volume of Virtual Fluid and steel (mL) Mass of steel ball (g) Analyze and Conclude 1. Calculating Use Table 1 to calculate the mass of the Virtual Fluid. How did you determine it? __________________________________________________________________ __________________________________________________________________ Use the formula below to calculate the density of the Virtual Mass Density --------------------Volume or dm ---V __________________________________________________________________ Floating Objects © Pearson Education, Inc. All rights reserved. 2. Calculating Fluid. Floating Objects 85 sx07CAGr8_VPhyLab_32.fm Page 86 Thursday, July 19, 2007 9:19 AM Name ___________________________ Date ___________________ Class ____________ 3. Problem Solving Archimedes’ principle states that the buoyant force acting on a submerged object is equal to the weight of the fluid the object displaces. You can determine the buoyant force on the steel sample by following these steps: First, determine the volume of Virtual Fluid displaced when the steel sample was placed in the Virtual Fluid. __________________________________________________________________ Second, determine the mass of the displaced Virtual Fluid. Use the formula for density. Rearrange the formula to solve for mass. __________________________________________________________________ Third, use the formula to calculate the mass of the Virtual Fluid. __________________________________________________________________ 4. Calculating The weight of an object is a measure of the force of gravity on that object. You can calculate the weight of an object (in newtons) by multiplying its mass (in kg) by 9.8 m/s2. Convert the mass of the Virtual Fluid to kg. Then calculate the weight of the displaced Virtual Fluid in newtons (N). __________________________________________________________________ 5. Drawing Conclusions What is the buoyant force acting on the steel ball? __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ 7. Relating Cause and Effect Explain why the steel ball sinks. __________________________________________________________________ Floating Objects __________________________________________________________________ 86 Floating Objects © Pearson Education, Inc. All rights reserved. 6. Drawing Conclusions What is the force of gravity (weight) acting on the steel ball? __________________________________________________________________ sx07CAGr8_VPhyLab_33.fm Page 87 Thursday, August 9, 2007 7:44 AM Name ___________________________ Date ___________________ Class ____________ Lab 33: Density and Buoyancy Purpose Density and Buoyancy To learn how to predict whether an object will float Background Why do some objects float and others sink? The answer lies in the density of the objects and the liquid they are placed in. Density is the mass of a material in one unit of volume. The mathematical formula for density is given below. Mass Density --------------------Volume or dm ---V The formula shows that the mass is divided by the volume to obtain the density. For this assignment, you will determine the density in g/mL of four solids and four liquids. With this information, you can make predictions about whether the solid materials will float in the liquids. Skills Focus Problem solving, predicting, calculating, drawing conclusions Procedure Density of a Solid 1. Start Virtual Physical Science. Select Density and Buoyancy from the list of assignments. The lab will open in the Density laboratory. © Pearson Education, Inc. All rights reserved. 2. Find the plastic sphere on the lab wall. Pick up the ball and drag it to the spotlight on the balance. Record the mass in Table 1. 3. Use the Up and Down arrows on the control panel to toggle through the options of fluids to use in the lab. Select the Virtual Fluid B. This is a unique Virtual Fluid that is used only in this virtual laboratory. Click the Full button underneath that display to select the amount of fluid to be added to the cylinder. Click the Fill button to release the chosen amount of fluid into the 250 mL graduated cylinder on the laboratory bench. Click on the cylinder to see a zoomed-in view of the level of the fluid. Record the volume of the Virtual Fluid in Table 1. 4. Drag the plastic ball to the top of the cylinder and drop it in the cylinder of Virtual Fluid. Click the green Drop button to let the ball fall into the fluid. Look at the close-up view window to note the new volume with both the Virtual Fluid and the plastic ball. Record the volume in the table. Density and Buoyancy 87 sx07CAGr8_VPhyLab_33.fm Page 88 Thursday, August 9, 2007 7:44 AM Name ___________________________ Date ___________________ Class ____________ Density and Buoyancy 5. Problem Solving How can you determine the volume of the plastic ball from your measurements? _________________________________________________________________ _________________________________________________________________ Record the volume of the plastic sample in Table 1. Click the handle at the bottom of the cylinder to empty the contents of the cylinder. 6. Repeat Steps 2–4 for three samples: ice, aluminum, and pine wood. Record your measurements in Table 1. Table 1 Sample Mass of Sample (g) Volume of Virtual Fluid (mL) Volume of Virtual Fluid and Sample (mL) Volume of Sample (mL) Density (g/mL) Plastic Ice Aluminum Pine Wood Density of a Liquid 8. Click the Tare button on the balance. Taring the balance rezeros the balance with whatever is on it. Drag the beaker on the counter to the balance and record its mass in Table 2. 9. Pick up the cylinder filled with ethanol and pour it into the empty beaker. Record the mass of the ethanol and beaker in Table 2. 10. Problem Solving How can you determine the mass of the ethanol in the beaker? _________________________________________________________________ 88 Density and Buoyancy © Pearson Education, Inc. All rights reserved. 7. Use the Up and Down arrows on the control panel to toggle through the options of fluids to use in the lab. Select Ethanol. Click the Full button underneath that display to select the amount of fluid to be added to the cylinder. Click the Fill button to release the chosen amount of fluid into the 250 mL graduated cylinder on the laboratory bench. Click on the cylinder to see a zoomed-in view of the level of the fluid. Record the volume in Table 2. sx07CAGr8_VPhyLab_33.fm Page 89 Thursday, August 9, 2007 7:44 AM Name ___________________________ Date ___________________ Class ____________ Record the mass of the ethanol in Table 2. Click the handle at the bottom of the cylinder to empty the contents of the cylinder. Drag the beaker to the container to the left of the Waste sign to empty the beaker. Density and Buoyancy 11. Repeat steps 7–9 to obtain the densities of water, olive oil, and mercury. Record your measurements in Table 2. Table 2 Sample Mass of Empty Beaker (g) Mass of Beaker and Sample (g) Mass of Sample (g) Volume of Sample (mL) Density (g/mL) Ethanol Water Olive Oil Mercury Analyze and Conclude 1. Calculating Use the formula for density to calculate the density of each of the solid samples. Record the answers in Table 1. 2. Calculating Use the same formula as above to calculate the density of each of the liquid samples. Record the answers in Table 2. 3. Applying Concepts Does the weight of an object or its density determine whether or not it will float in a fluid? Explain. __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ © Pearson Education, Inc. All rights reserved. 4. Predicting Which of the solids will float in the olive oil? Explain. __________________________________________________________________ __________________________________________________________________ Test your prediction by filling the cylinder with olive oil. Then move the dispenser head over the next cylinder by clicking it and dragging it until it clicks in place above the cylinder. Fill four cylinders with olive oil. Place each of the objects in one of the cylinders and release them all to see whether or not they will float. 5. Predicting Which of the solids will sink in mercury? Explain. __________________________________________________________________ __________________________________________________________________ Empty all of the cylinders by clicking the release switches at the bottom of the cylinders. Now test your prediction by filling all of the cylinders with mercury. Place a different object in each one of the cylinders and release them all to see whether or not they will sink. Density and Buoyancy 89 sx07CAGr8_VPhyLab_33.fm Page 90 Thursday, July 19, 2007 9:23 AM Name ___________________________ Date ___________________ Class ____________ Density and Buoyancy 6. Predicting What would you observe if olive oil and water were poured together? __________________________________________________________________ __________________________________________________________________ Test your prediction by half filling one of the cylinders with olive oil by clicking the 1/2 button on the dispenser control before filling. That will allow you to add half a cylinder of oil, then toggle through the fluids and select water and dispense 1/2 of a fill of water to the same cylinder. 7. Drawing Conclusions If all four solids and all four liquids were mixed in the same cylinder at the same time, what would you observe? List what you would see from the top of the cylinder to the bottom. Explain how you determined your placement. __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ © Pearson Education, Inc. All rights reserved. 90 Density and Buoyancy sx07CAGr8_VPhyLab_34.fm Page 91 Thursday, August 9, 2007 2:49 PM Name ___________________________ Date ___________________ Class ____________ Lab 34: The Work of the Egyptians Problem To compare the amount of work needed to lift a 50m block of cement to the amount of work and power needed to push the same block up a ramp Background The Work of the Egyptians The Egyptians were able to build enormous pyramids because of their understanding of the potential of the inclined plane. Because the Egyptians were limited to manpower force to move each block of stone, they used ramps as machines. Without an understanding of simple machines, manpower alone could not have moved or lifted the blocks of stone—some with an average weight of 2.5 tons each—that were used to build the pyramids. In this lab, you will learn the relationship between work and power and the value of even simple machines. Skills Focus Interpreting data, drawing conclusions, inferring Procedure 1. Start Virtual Physical Science and select The Work of the Egyptians from the list of assignments. The lab will open in the Mechanics laboratory. Note that the laboratory will be set up with a sled at the bottom of the screen and attached to the sled will be a rocket used to push the sled up in the air. 2. You will first push the sled straight up in the air and measure the force that it takes to lift it up. Then push the sled up a ramp and measure the different forces it takes to move up ramps of different angles. © Pearson Education, Inc. All rights reserved. 3. The mass of the sled is 50 kg. What is the weight of the sled? Remember weight mass 3 acceleration due to gravity. Acceleration due to gravity 9.8m/s2. Weight of sled The Work of the Egyptians 91 sx07CAGr8_VPhyLab_34.fm Page 92 Friday, August 10, 2007 12:16 PM Name ___________________________ Date ___________________ Class ____________ 4. Determine the least amount of force necessary to lift the sled 50m. Change the amount of force until you have the smallest force necessary to push the sled to the top of the screen, which is 50m high. Click the Force button to start the rocket for each trial. Watch the Y display at the bottom and stop when the sled reaches 50m. If you have too much or too little force then use the Reset button to reset and use the Parameters palette to increase or decrease the force for the next trial. Record the approximate amount of time it took the sled to reach the top. You may want to use the Time Acceleration buttons to speed up time to make it to the top sooner. Click the or signs by the Acceleration Display. The Work of the Egyptians Minimum Pushing Force Time to reach top 5. Now find the least amount of force necessary to push the sled to the same height using ramps of different angles. Notice that the table is made of cement and the sled is made of cement. You will push the sled with different amounts of force and watch it slide up the ramp. Inferring. If the angle of the ramp is changed, what must change in order to have the sled reach the same height as before (50m)? _________________________________________________________________ 92 The Work of the Egyptians © Pearson Education, Inc. All rights reserved. 6. Drag the Ramp icon on the tray at the top of the screen down into the experiment area. Also pull down the friction icon (the ramp with a sled icon already on it). Use the Ramp section in Parameters to change the angle of the ramp and the length as indicated in the table below. (You already completed the first row in the experiment.) To find the force necessary to push the sled to the top, pick up the sled and drag it to the bottom of the ramp, where Y 0. After each attempt, use the Reset button and make the necessary changes before you begin your next trial. Complete Data Table 1 using the same technique as in steps 5 and 6. sx07CAGr8_VPhyLab_34.fm Page 93 Thursday, August 9, 2007 2:49 PM Name ___________________________ Date ___________________ Class ____________ Data Table 1 Ramp Angle Ramp Length (m) Force (N) 90° 50 491 60° 57.74 45° 70.71 30° 100 10° 287.94 7. Compute the work and power required to move the sled for each ramp. Use Data Table 2 to compute work for each ramp. Remember the equations for work force 3 distance. Data Table 2 Force (N) Ramp Length (m) 90° 50 60° 57.74 45° 70.71 30° 100 10° 287.94 The Work of the Egyptians Ramp Angle Work (J) Analyze and Conclude 8. Recall Why did the length of the ramp need to change for the ramps of different angles? _________________________________________________________________ _________________________________________________________________ © Pearson Education, Inc. All rights reserved. _________________________________________________________________ 9. Analyze How did the pushing force change when the ramp angle changed? _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ 10. Analyze How does changing the distance you have to push the sled affect the work required? _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ The Work of the Egyptians 93 sx07CAGr8_VPhyLab_34.fm Page 94 Thursday, August 9, 2007 2:49 PM Name ___________________________ Date ___________________ Class ____________ 11. If you had to help the Egyptians build a pyramid, explain which ramp you would use and why you would want them to use it? _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ The Work of the Egyptians _________________________________________________________________ © Pearson Education, Inc. All rights reserved. 94 The Work of the Egyptians sx07CAGr8_VPhyLab_35.fm Page 95 Thursday, August 9, 2007 2:50 PM Name ___________________________ Date ___________________ Class ____________ Lab 35: Falling Elevator Problem To determine and understand the amount of force needed to bring an elevator to a certain height and relate the work and power of the pulley system Background Skyscrapers are vital to the economies of large cities where there is limited area for buildings. Stacking floors, as seen in high rises and skyscrapers, saves space and allows for more office or living area. However, these tall buildings would be impractical without elevators. Elevators make it possible to transport people quickly and easily to all the floors. The cable elevator, which uses a pulley, is the most popular today. Skills Focus Predicting, interpreting data, drawing conclusions Procedure 1. Start Virtual Physical Science and select Falling Elevator from the list of assignments. The lab will open in the Mechanics laboratory. 3. Click the Force button to turn on the rocket force and watch the sled accelerate into the air. Now change the amount of force to find a range of seconds that it would take to raise the elevator. First click the Reset button to reset the lab, then open the Parameters Palette by clicking on the Parameters button. Under the Force section you will see a text box where you can enter different values for the force. Increase or decrease the amount of force to push the elevator. After you change the force value, you need to click somewhere else in the palette, or click Enter. Find the smallest force that will lift the elevator. Record your trial forces in Data Table 1. Also include the time it took for each trial. Use 0 in the time box to indicate if the force was too little to lift the elevator. Falling Elevator © Pearson Education, Inc. All rights reserved. 2. The laboratory will be set up with a sled located at the bottom of the screen. The sled represents the elevator. A rocket is attached to the base of the sled. You will use the rocket to accelerate the elevator to the designated height. Calculate the height in meters by estimating that each floor of the skyscraper is about 12 feet tall. Note that 1m is about 3 ft. 4. The mass of the sled represents a typical full capacity elevator, which is about 3000kg. Falling Elevator 95 sx07CAGr8_VPhyLab_35.fm Page 96 Thursday, August 9, 2007 2:50 PM Name ___________________________ Date ___________________ Class ____________ Data Table 1 Mass (kg) 3000 3000 3000 3000 3000 Height (number of floors) Height (in meters) Force (N) Time (s) 20 20 20 20 20 Predict. What would the force required if you changed the mass to half capacity, which would be as if the elevator was half full. __________________________________________________________________ __________________________________________________________________ 5. Change the mass of the sled, first click the Reset button and then open the Parameters Palette and open the Object section. Change the mass to 1500kg and then re-run the experiment for this new mass following the procedure described in step 3. Record your new data in Data Table 2. Mass (kg) 1500 1500 1500 1500 1500 Height (number of floors) 20 20 20 20 20 Force (N) Time (s) 6. Determine the work and power required for both the full and half-full elevators. Use the data from your trials that used sma ll forces. Remember that work force 3 distance and power work/time. If any of your calculations took long enough to output time in minutes, remember to convert the time to seconds. 96 WORK Full Elevator Half Full Force (N) Distance (m) Work (J) POWER Full Elevator Half Full Work (J) Time (s) Power (watts) Falling Elevator © Pearson Education, Inc. All rights reserved. Falling Elevator Data Table 2 sx07CAGr8_VPhyLab_35.fm Page 97 Thursday, August 9, 2007 2:50 PM Name ___________________________ Date ___________________ Class ____________ Analyze and Conclude 7. Which elevator required the most work to move? Why? __________________________________________________________________ 8. How can pulleys help reduce the amount of power required? __________________________________________________________________ 9. Think about the three types of pulleys. Why would you not use a single fixed pulley to lift an elevator? __________________________________________________________________ 10. Using the table showing examples of horsepower related objects, explain why there is a limit to the maximum load an elevator may carry. 1 horsepower is approximately equal to 750 watts. Watts Horsepower Example 0–5000 0–6.7 Lawnmower 5001–10000 6.7–13.4 Electric motor bike 10001–15000 13.4–20.1 Riding lawn mower 15001–20000 20.1–26.8 Small air compressor 20001–30000 26.8–40.2 Small boat motor 30001–40000 40.2–53.6 Hot water boiler 40001–50000 53.6–67 Large air compressor 50001–100000 68–134 Small car engines 100001–500000 134–670 Muscle cars +500000 +670 Airplanes © Pearson Education, Inc. All rights reserved. Falling Elevator Falling Elevator 97 sx07CAGr8_VPhyLab_36.fm Page 98 Friday, August 10, 2007 12:17 PM Name ___________________________ Date ___________________ Class ____________ Lab 36: Thermal Energy Problem To calculate the amount of kinetic energy in a system and and observe how energy changes when an outside force is applied Background What do you feel when you touch a hot frying pan? What do you feel when you sit down on your car seat after your car has been sitting in the sun? What do you feel when you pick up a plastic cup full of hot water? You feel the burn of heat! These are examples of how you notice thermal energy. All matter contains atoms, which move randomly throughout the substance. These atoms have kinetic energy. Some objects are rigid solids, so the atoms aren’t as free to move around, but they still have the potential to move and, in fact, are moving slightly. The total potential and kinetic energy of an object make up its thermal energy. Skills Focus Predicting, drawing conclusions, graphing, making models Procedure 1. Start Virtual Physical Science and select Thermal Energy from the list of assignments. The lab will open in the Mechanics laboratory. Thermal Energy 3. Click on the Lab Book at the top of the screen to open it. Click the Red button in the Recording section to start recording the data. Click the green Start button to start the balls in motion. After a few seconds click the Pause button to stop recording data. You will need to record the mass of each ball and the velocity of each ball. You can find the mass of the balls in the Parameters Palette under Objects. Record the data in the table below. Record the velocities of each of the balls from the same period of time. The number of the ball that is currently being tracked is located in the bottom right of the screen. Use the arrows to scroll through each ball and record its total velocity in Data Table 1. This value is located at the bottom of the screen in the first row, second column (Vtot). Using the formula for Kinetic Energy = 1/2m·v2, where m is the mass and v is the velocity, calculate the kinetic energy for each ball and record the total in the last row. 98 Thermal Energy © Pearson Education, Inc. All rights reserved. 2. The laboratory will be set up with 10 balls which represent molecules inside of a substance. The system is enclosed by a box and thus the energy is conserved. You will see that the atoms are in random motion. The kinetic energy of the substance is calculated by adding up the kinetic energies of all the particles that make it up. sx07CAGr8_VPhyLab_36.fm Page 99 Friday, August 10, 2007 12:18 PM Name ___________________________ Date ___________________ Class ____________ Data Table 1: Energy Level 1 Ball Number Mass (kg) 1 2 3 4 5 6 7 8 9 10 10 20 10 15 5 1 100 200 7 1000 Kinetic Energy (J) Velocity (m/s) Total Kinetic Energy Predicting. What will happen to the balls in the system when apply an outside force? 4. Now place the plunger onto one of the balls in any direction you choose. Do not reset the lab. Click the Force button to fire the plunger. This outside force will change the velocity of the ball and change its kinetic energy. Wait a few seconds to ensure the ball has transferred its energy to the system, then click the Pause button. Again gather the total velocity for each ball. Use the new table below to record the data for the new energy level of the system. Ball Number Mass (kg) 1 2 3 4 5 6 7 8 9 10 10 20 10 15 5 1 100 200 7 1000 Kinetic Energy (J) Velocity (m/s) Thermal Energy © Pearson Education, Inc. All rights reserved. Data Table 2: Energy Level 2 Total Kinetic Energy Thermal Energy 99 sx07CAGr8_VPhyLab_36.fm Page 100 Thursday, August 9, 2007 2:58 PM Name ___________________________ Date ___________________ Class ____________ 5. Repeat step 4 again, hitting one of the balls with the plunger and adding more energy to the system. Record the data in the Data Table 3. Data Table 3: Energy Level 3 Ball Number Mass (kg) 1 2 3 4 5 6 7 8 9 10 10 20 10 15 5 1 100 200 7 1000 Kinetic Energy (J) Velocity (m/s) Total Kinetic Energy 2 Analyze and Conclude 7. Which energy level had the highest total kinetic energy? _________________________________________________________________ 8. If this were representing a molecule made up of many different atoms, at which energy level would it be the most effective to use to heat up another molecule? Why? _________________________________________________________________ 9. How could this model be used to represent energy transfer within a molecule? _________________________________________________________________ Thermal Energy 10. Make a bar graph of your data. On the x-axis you will graph the energy level. On the y-axis you will graph the total kinetic energy. 100 Thermal Energy © Pearson Education, Inc. All rights reserved. 6. Go back and calculate the total kinetic energy for the system at the different energy levels. Calculate the kinetic energy for each part of the system then add them together. Use the column on the right to record the numbers for each ball and then total those at the bottom in the total cell. Remember Kinetic Energy 1--- mv2. sx07CAGr8_VPhyLab_37.fm Page 101 Monday, August 13, 2007 2:19 PM Name ___________________________ Date ___________________ Class ____________ Lab 37: Potential Energy to Kinetic Energy Purpose Potential Energy to Kinetic Energy To study the conversion of potential energy to kinetic energy by observing the movement of an object down a ramp Background The conversion of energy between potential energy and kinetic energy is a process that is observed throughout our daily lives. Any time an object falls off of any height and speeds up as it falls to the ground, we are observing a transformation of energy. Skills Focus Predicting, interpreting data, drawing conclusions Procedure 1. Start Virtual Physical Science and select Potential Energy to Kinetic Energy from the list of assignments. The lab will open in the Mechanics laboratory. 2. The laboratory will be setup with a sled on a ramp and with gravity pulling vertically down. The surface is frictionless. You will release the sled from different heights and watch it slide down the ramp. You will measure the speed of the sled at the base of the ramp and use that to calculate the kinetic energy. © Pearson Education, Inc. All rights reserved. 3. Predicting Where on the ramp do you think the sled has the most total energy? At the top, somewhere in the middle of the slope, or at the bottom where the sled is moving fastest? __________________________________________________________________ 4. You will be measuring the height of the sled and the speed of the sled when it hits the bottom. In Data Table 1 record the Y height of the sled, found in the left hand side of the data table at the bottom of the screen next to Y. Click the red Start button in the Experiment Control panel to release the sled. It will slide to the bottom of the ramp and explode when it hits the bottom. Record the total velocity found in the display next to V tot. 5. Now repeat the experiment four more times, starting the sled in a different place every time. Click the blue Reset button to return the sled to the top of the ramp. Click on the sled and move it down the ramp to a different height. Remember to record the Y height in the table and then start it sliding by clicking Start. Record the total velocity in the Data Table 1 after each run. Potential Energy to Kinetic Energy 101 sx07CAGr8_VPhyLab_37.fm Page 102 Monday, August 13, 2007 2:20 PM Name ___________________________ Date ___________________ Class ____________ Data Table 1 Potential Energy to Kinetic Energy Height of the Sled (Y) (m) Speed at the bottom (Vtot) (m/s) Initial Potential Energy (J) Final Kinetic Energy (J) 6. To calculate the potential energy of the sled, you need to know its mass. Click on Parameters and select Objects to find the mass of the object. Gravitational potential energy is calculated with the following formula: PE = mgh, where m is the mass of the object in kilograms, g is the gravitational constant = 9.8 m/s2, and h is the height of the object in meters. Calculate and record in the table the initial potential energy of the object for the five cases that you tried. 7. Now compute the kinetic energy of the object at the end of the ramp. Kinetic energy is calculated by knowing the mass of the object and the velocity. KE = 1--- mv2, where m is the mass of the object in kilograms and v is 2 the velocity, or speed, of the object. Calculate and record in the table the final kinetic energy of the object in the five cases you tried. 9. Now measure the energy of the sled throughout the course of a run. Reset the experiment and in Data Table 2 record the initial height of the sled and its speed as explained in step 5. Start the sled moving down the ramp and somewhere in the middle of the ramp click Pause and record the Y height and speed. Start the sled sliding again and let it slide to the bottom of the ramp. Record the Y height and speed in the table again. 10. Calculate the potential and kinetic energies at each step as explained in steps 6 and 7. 102 Potential Energy to Kinetic Energy © Pearson Education, Inc. All rights reserved. 8. Interpreting Data What do you notice about the quantities you just calculated for initial potential energy and final kinetic energy? __________________________________________________________________ sx07CAGr8_VPhyLab_37.fm Page 103 Friday, August 10, 2007 8:09 AM Name ___________________________ Date ___________________ Class ____________ Data Table 2 Height of the Sled (Y) (m) Speed (Vr) (m/s) Potential Energy (J) Kinetic Energy (J) Potential Energy to Kinetic Energy Initial: Middle: Bottom: 11. The ramp has been set at an angle of 45 degrees for all of the previous experiments. Now you will change the angle of the ramp and measure the energy of the sled when released on different slope ramps. Reset the experiment. 12. You can copy your first row of data from Data Table 1 into the first row of Data Table 3. Now in the Parameters Ramp section change the angle of the ramp to the next angle listed in the table and move the sled down the ramp to the same Y height that it was at in the first run. Click Start to run the experiment and record the speed at the bottom as described in step 4. Calculate the kinetic energy for that run. Reset the experiment and change the ramp again to the next listed angle. Repeat the experiment as described above. If necessary increase the length of the ramp to be able to place the sled at the same initial height. Data Table 3 Ramp Angle Height of the Sled (Y) (m) Speed at the bottom (Vr) (m/s) Kinetic Energy (J) 45° 60° 15° © Pearson Education, Inc. All rights reserved. Your choice: ___ Analyze and Conclude 1. Analyze How did the kinetic energy change by changing the angle? __________________________________________________________________ 2. Analyze How did the kinetic energy change throughout the course of sliding down the ramp? How did the total energy (kinetic and potential) change throughout a run? __________________________________________________________________ 3. Where is energy generally lost to as objects move in real life? __________________________________________________________________ Potential Energy to Kinetic Energy 103 sx07CAGr8_VPhyLab_38.fm Page 104 Monday, August 13, 2007 2:22 PM Name ___________________________ Date ___________________ Class ____________ Lab 38: Temperature and Volume of a Gas Purpose To learn about the relationship between the temperature and the volume of a gas Background Charles’s Law was discovered by Joseph Louis Gay-Lussac in 1802 based on unpublished work done by the French scientist Jacques Charles in about 1787. Charles’s law describes the relationship between the temperature of a gas and its volume. You will make observations similar to those made by Charles. You will change the temperature of a gas while keeping all other variables constant and observe what happens to the volume of the gas. Temperature and Volume of a Gas Skills Focus Graphing, predicting, interpreting data, controlling variables, drawing conclusions Procedure 1. Start Virtual Physical Science and select Temperature and Volume of a Gas from the list of assignments. The lab will open in the Gases laboratory. Note that the balloon in the chamber is filled with a gas at a temperature of 100°C. The pressure of the gas is 101.3 kPa. Its volume is 1531 cm3. 3. Record in the table the beginning temperature and volume of the gas. Click on the 1 in the temperature window. The digit should turn green. Type 2, so that the temperature is now 200°C. Record the new temperature and volume in the table. Repeat this step again but type a 3 in the temperature window. Again, record your data. Continue to increase the temperature by 100°C each time and record your data until you reach 700°C. Temperature (°C) 104 Temperature and Volume of a Gas Volume (cm3) © Pearson Education, Inc., publishing as Pearson Prentice Hall. All rights reserved. 2. Predicting You are going to increase the temperature of the gas in the balloon. What effect will the change in temperature have on the volume of the balloon? Record your prediction. __________________________________________________________________ sx07CAGr8_VPhyLab_38.fm Page 105 Friday, August 10, 2007 8:05 AM Name ___________________________ Date ___________________ Class ____________ Analyze and Conclude Temperature and Volume of a Gas © Pearson Education, Inc., publishing as Pearson Prentice Hall. All rights reserved. 1. Graphing Make a line graph of the data obtained in Step 3. Show temperature in °C on the horizontal axis and volume in cm3 on the vertical axis. 2. Drawing Conclusions Did the results you obtained support your prediction? Explain. __________________________________________________________________ 3. Interpreting Graphs Is the relationship between temperature and volume linear or nonlinear? __________________________________________________________________ 4. Predicting If the temperature were decreased, how would the volume of the gas change? __________________________________________________________________ To check your prediction, decrease the temperature on the balloon by pulling down on the lever on the temperature controller until the tens digit turns blue and holding the lever. Observe the balloon’s volume as the temperature decreases. Temperature and Volume of a Gas 105 sx07CAGr8_VPhyLab_39.fm Page 106 Monday, August 13, 2007 2:39 PM Name ___________________________ Date ___________________ Class ____________ Lab 39: Specific Heat Purpose To measure the specific heat of several different metals to better understand the implications of heat capacity on product design. Background On a hot summer day, it is always refreshing to jump into a pool because the water is cooler than the air around you and the ground that is roasting your feet. This may seem strange since the water and ground are being heated by the same source—the sun. This evidence suggests it takes more heat to raise the temperature of some substances than others, which is true. The amount of heat required to raise the temperature of 1 g of a substance by 1 degree Celsius is called the specific heat capacity, or specific heat, of that substance. In this experiment, you compare the specific heats of various metals to see how the specific heat of the metal affects how fast it changes temperature and you will see why soda cans are made out of the material they are made out of. Skills Focus Measuring, calculating, applying concepts, making judgments Procedure 2. You will be measuring the heat capacity of Al, Au, and Stainless Steel. Make sure to keep track of which sample you are testing by keeping accurate notes. Click on the Lab Book to open it. Record the mass of Al on the balance. If it is too small to read click on the Balance area to zoom in, record the mass of Al in the Data Table, and return to the laboratory. 3. Pick up the Al sample from the balance pan and place the sample in the oven. Click the oven door to close. The oven is set to heat to 200°C. 4. The calorimeter has been filled with 100 mL water. The density of water at 25°C is 0.998 g/mL. Use the density of the water to determine the mass from the volume and record the volume and mass in the Data Table. Make certain the stirrer is On (you should be able to see the shaft rotating). Click the thermometer window to bring it to the front and click Save to begin recording data. Allow 20-30 seconds to obtain a baseline temperature of the water. 5. Click on the Oven to open it. Drag the hot aluminum sample from the oven until it snaps into place above the calorimeter and drop it in. Click the thermometer and graph windows to bring them to the front again and 106 Specific Heat © Pearson Education, Inc. All rights reserved. Specific Heat 1. Start Virtual Physical Science and select Specific Heat from the list of assignments. The lab will open in the Calorimetry laboratory. sx07CAGr8_VPhyLab_39.fm Page 107 Monday, August 13, 2007 2:39 PM Name ___________________________ Date ___________________ Class ____________ observe the change in temperature in the graph window until it reaches a constant value and then wait an additional 20–30 seconds. Click Stop in the thermometer window. (You can click on the clock on the wall labeled Accelerate to accelerate the time in the laboratory.) A blue data link will appear in the lab book. Click the blue data link and in the Data Table record the temperature before adding the Al and the highest temperature after adding the Al. (Remember that the water will begin to cool down after reaching the equilibrium temperature.) 6. Repeat the experiment with an Au sample. Click the red disposal bucket to clear the lab. Click on the Stockroom to enter. Double-click the Dewar calorimeter to move it to the Stockroom counter. Click the metal sample cabinet. Open the top drawer (the samples are alphabetically arranged) by clicking on it, select the Au by double-clicking and zoom out. Double-click on the Petri dish with the selected sample to move it to the Stockroom counter. Return to the laboratory. 7. Move the Petri dish with the sample to the spotlight next to the balance. Move the metal sample to the balance pan and record the mass in the Data Table. Return to the laboratory. Specific Heat 8. Double-click the calorimeter to move it into position in the laboratory. Click the oven to open the door. Move the metal sample from the balance pan to the oven and click to close the oven door. Click above the tens place several times on the front of the oven to change the temperature to 200°C. Fill the 100 mL graduated cylinder with water by holding it under the tap until it returns to the counter and then pour it into the calorimeter. Turn on the stirrer. Turn on the thermometer. Click on the Graph and Save buttons. Move your metal sample from the oven to the calorimeter. Follow the procedures used with Al to obtain the equilibrium temperature. Record all of your observations in the Data Table. Repeat for steel. © Pearson Education, Inc. All rights reserved. Data Table Al Au Stainless Steel mass of metal (g) volume of water (mL) mass of water (g) initial temperature of water (°C) initial temperature of metal (°C) max temp of water + metal (°C) Specific Heat (J/g°C) Specific Heat 107 sx07CAGr8_VPhyLab_39.fm Page 108 Monday, August 13, 2007 2:39 PM Name ___________________________ Date ___________________ Class ____________ Analyze and Conclude 9. Determine the changes in temperature of the water (ΔTwater). 10. Calculate the heat (q) gained by the water using the following equation: qwater = mwater • Twater, • Cwater given = 4.184 J/(g°C) 11. Determine the changes in temperature of the Al (ΔTAl). 12. Remembering that the heat gained by the water is equal to the heat lost by the metal, calculate the specific heat of the metal. qwater = qmetal = mAl• TAl• CAl which when solved for the heat q ( m metal ) ( T metal ) metal . Record your result in the Table. capacity is: CAl = ---------------------------------------------- 13. Repeat the calculation of specific heat capacity for Au and record your result in the Data Table. Specific Heat 15. Applying Concepts Heat capacity is a numerical way to express how much heat it takes to heat something up 1 degree. So an object with low heat capacity requires very little heat to heat it up, while an object with high heat capacity takes a lot of heat to change its temperature. If you have a can made of gold and one made of aluminum, describe what will happen to the temperature of the can when you pull it out of the refrigerator. Include in your discussion connections to the specific heat of the metals. 16. Making Judgements Many cooking pans are made out of steel and there are also some made of aluminum. Discuss which type of pan you think would be better. __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ 108 Specific Heat © Pearson Education, Inc. All rights reserved. 14. Repeat the calculation of specific heat capacity for Steel and record your result in the Data Table. sx07CAGr8_VPhyLab_40.fm Page 109 Tuesday, August 14, 2007 6:29 AM Name ___________________________ Date ___________________ Class ____________ Lab 40: Blackbody Radiation Purpose To study the radiation emitted by a glowing metal filament Background In the early 1900s several experimental results appeared to be in conflict with classical physics. One of these experiments was the study of blackbody radiation. A blackbody is a solid (such as a piece of iron) that does not emit light at low temperatures, but, when heated, the blackbody begins to emit first red and then orange light and at higher temperatures eventually becomes white hot. The intensity of the emitted light is also a function of temperature. In this lab, you will make observations of the radiation emitted by a tungsten filament, the same type of metal that is used in incandescent light bulbs. Skills Focus Measuring, graphing, interpreting graphs, drawing conclusions, developing hypotheses Procedure 1. Start Virtual Physical Science and select Blackbody Radiation from the list of assignments. The lab will open in the Quantum laboratory. A metal sample holder with tungsten metal will be on the lab bench with an electric heater set at a temperature of 3000 K. A spectrometer is on the right and is switched on (the spectrometer window is open). Blackbody Radiation © Pearson Education, Inc. All rights reserved. 2. The spectrometer detects the intensity of the emitted light as a function of the wavelength (or frequency). In the grid on the next page draw the spectrum detected by the spectrometer with wavelength (in nm) on the x-axis and intensity on the y-axis. Blackbody Radiation 109 sx07CAGr8_VPhyLab_40.fm Page 110 Tuesday, August 14, 2007 6:29 AM Name ___________________________ Date ___________________ Class ____________ If you drag your cursor over a peak, it will identify the wavelength (in nm) in the x-coordinate field in the bottom right corner of the detector window. Record the wavelength of the peak in the data table. (Round to whole numbers.) Data Table Temperature (K) 3000 3100 3200 3300 Blackbody Radiation 3400 3500 3600 110 Blackbody Radiation Wavelength (nm) © Pearson Education, Inc. All rights reserved. 3. Change the temperature on the heater to 3100 K by clicking on the button above the hundreds place on the heater LCD controller. Record the shape of the curve on the same graph (label each line with a temperature) and the wavelength of the peak intensity in the data table. Continue with temperatures of 3200 K, 3300 K, 3400 K, 3500 K, and 3600 K. If you raise the temperature to 3700 K you will have to start over. Click on the Reset Lab button just under the Danger sign, enter the Stockroom, click on the clipboard and select Preset Experiment #3: Blackbody Radiation. sx07CAGr8_VPhyLab_40.fm Page 111 Tuesday, August 14, 2007 6:29 AM Name ___________________________ Date ___________________ Class ____________ 4. What observations can you make about the shape of the curve as temperature changes? __________________________________________________________________ __________________________________________________________________ 5. The visible portion of the electromagnetic spectrum occurs between 400 nm and 700 nm. Mark the visible spectrum on your graph. Interpreting Graphs Does the peak intensity ever occur in the visible region? Does this mean that there is no visible light radiated over this temperature range? Explain. __________________________________________________________________ __________________________________________________________________ 6. Drawing Conclusions You can see on the graph that many different wavelengths of electromagnetic radiation are emitted as the tungsten is heated. The peak in the curve, or area where the most radiation is emitted, is at a longer wavelength than visible light. This range is called the infrared region, which humans can't see with their eyes, but can feel as heat. The metal in heat lamps also radiates infrared rays as it heats up, but you can see the coils glowing because it also emits some light in the visible range, just like this tungsten. As the temperature increases, what do you notice about the intensity or the peak height? As a light bulb heats up, should it radiate more light? __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ 7. Developing Hypotheses Light bulbs are actually built to limit the amount of electrical power they can draw, to limit how fast they can burn out. Light bulbs do burn out though, why do you think that is? __________________________________________________________________ __________________________________________________________________ Blackbody Radiation © Pearson Education, Inc. All rights reserved. __________________________________________________________________ Blackbody Radiation 111 sx07CAGr8_VPhyLab_41.qxd 8/14/07 7:17 AM Page 112 Name ___________________________ Date ___________________ Class _____________ Lab 41: Wave Properties of Light Wave Properties of Light Purpose To study the single slit and double slit diffraction experiments Background It has long been known that if you shine light through narrow slits that are spaced at small intervals, the light will form a diffraction pattern. A diffraction pattern is a series of light and dark patterns caused by wave interference. The wave interference can be either constructive (light patterns) or destructive (dark patterns). In this experiment, you will shine a laser through a device with two slits where the spacing can be adjusted and investigate the patterns that will be made at a distance from the slits. Skills Focus Predicting, drawing conclusions, observing Procedure 1. Start Virtual Physical Science and select Wave Properties of Light from the list of assignments. The lab will open in the Quantum laboratory. 2. What source is used in this experiment and for what reason? What is the wavelength of the Laser? In the space below, draw a picture of the pattern displayed on the video screen. 112 Wave Properties of Light © Pearson Education, Inc. All rights reserved. What is the spacing of the two slits on the two slit device? sx07CAGr8_VPhyLab_41.qxd 8/14/07 7:17 AM Page 113 Name ___________________________ Date ___________________ Class _____________ 3. Change the Intensity of the Laser from 1 nW to 1W. Does the intensity of the light affect the diffraction pattern? Wave Properties of Light Change the Slit Spacing to 1 m. Observe the pattern displayed on the video screen as you change the slit spacing from 1 m to 7 m by one-micrometer increments. What can you state about the relationship between slit spacing and diffraction pattern? 4. Predicting What do you think would happen if you made the spacing between the slits smaller than the size of the wavelength? What will happen if the spacing between the slits is greater than the size of the wavelength? 5. Drawing Conclusions When the slits are very close together, it appears to be just one slit, and we see a basic diffraction pattern; however, once we spread out the slits, we can start to see interference when waves passing through the two different slits interfere with each other. Confirm your prediction above and write your observation of the difference in the diffraction patterns between spacings less than and greater than the wavelength size. © Pearson Education, Inc. All rights reserved. 6. Increase the Wavelength of the Laser to 700 nm. What affect does an increase in the wavelength have on the diffraction pattern? Wave Properties of Light 113 sx07CAGr8_VPhyLab_41.qxd 8/14/07 7:17 AM Page 114 Wave Properties of Light Name ___________________________ Date ___________________ Class _____________ 7. Observing Decrease the Intensity on the Laser to 1000 photons/second. Click on the Persist button on the video camera to look at individual photons coming through the slits. Observe for one minute. What observation can you make about this pattern as compared to the pattern from the continuous beam of photons? Decrease the Intensity to 100 photons/second. Observe for another minute after clicking Persist. At these lower intensities (1,000 and 100 photons/second), there is never a time when two photons go through both slits at the same time. How can a single photon diffract? 8. Drawing Conclusions From this experiment, what conclusions can you make about the nature of light? © Pearson Education, Inc. All rights reserved. 114 Wave Properties of Light sx07CAGr8_VPhyLab_42.qxd 8/16/07 12:51 PM Page 115 Name ___________________________ Date ___________________ Class _____________ Lab 42: Particle Properties of Light Purpose To study the photoelectric effect and understand the connection between the wavelength and energy of photons. Background Particle Properties of Light Though Albert Einstein is most famous for E mc2 and his work in describing relativity in mechanics, his Nobel Prize was for understanding a very simple experiment. It was long understood that if you directed light of a certain wavelength at a piece of metal, it would emit electrons. In classical theory, the energy of the light was thought to be based on its intensity and not its frequency. However, the results of the photoelectric effect contradicted classical theory. These inconsistencies led Einstein to suggest that we need to think of light as being comprised of particles (photons) and not just as waves. The energy of a photon is directly proportional to the frequency of light, and inversely proportional to the wavelength of light. This means that light of longer wavelengths has less energy than light of shorter wavelengths. You will be using light of different wavelengths and you will compare and rank the amounts of energy. Skills Focus Observing, comparing and contrasting, drawing conclusions Procedure 1. Start Virtual Physical Science and select Particle Properties of Light from the list of assignments. The experiment opens in the Quantum laboratory. © Pearson Education, Inc. All rights reserved. 2. What source is used in this experiment and what does it do? At what intensity is the laser set? At what wavelength is the laser set? Record the wavelength (in nm) in the data table. Which metal foil is used in this experiment? Particle Properties of Light 115 sx07CAGr8_VPhyLab_42.qxd 8/21/07 12:28 PM Page 116 Name ___________________________ Date ___________________ Class _____________ What detector is used in this experiment and what does it measure? Turn on the detector by clicking on the red/green light switch. What does the signal on the phosphor screen indicate about the laser light shining on the sodium foil? 3. Decrease the Intensity to 1 photon/second. How does the signal change? Particle Properties of Light Increase the Intensity to 1 kW. How does the signal change? 4. Change the Intensity back to 1 nW and increase the Wavelength to 600 nm. What do you observe? Record the wavelength in the data table. Determine the maximum wavelength at which emission of electrons occurs in the metal. Wavelength (nm) Energy Light color 5. Rank the amount of energy of each wavelength of light. Determine the color of the light by clicking on the Spectrum Chart (just behind the laser); the markers indicate what color is represented by the wavelength selected. Record the colors in the table. 116 Particle Properties of Light © Pearson Education, Inc. All rights reserved. Data Table sx07CAGr8_VPhyLab_42.qxd 8/14/07 7:16 AM Page 117 Name ___________________________ Date ___________________ Class _____________ 6. Comparing and Contrasting What is the difference between intensity and wavelength? Which matters in the formation of photoelectrons: intensity or wavelength? 7. Drawing Conclusions Summarize what you have observed about which wavelengths and energies of light can cause electrons to be emitted from a metal plate. Include a description of the effect of varying the intensity of light on the amount of electrons emitted. © Pearson Education, Inc. All rights reserved. Particle Properties of Light Particle Properties of Light 117 sx07CAGr8_VPhyLab_43.fm Page 118 Tuesday, August 14, 2007 7:21 AM Name ___________________________ Date ___________________ Class ____________ Lab 43: Atomic Emission Spectra Purpose To study the colors of light emitted as a current is passed through various gases used in common lighting devices Background In the 1800s, scientists found that when a sample of gas was excited by an electric field, light with only certain discrete wavelengths was emitted. This property allowed for the development of spectroscopic techniques that can be used in the identification and analysis of elements and compounds. Niels Bohr, a Danish physicist, first proposed that energy levels of electrons are quantized and that excited electrons can only fall to discrete energy levels, which explains why when electricity was run through a gas, it did not emit all colors in the visible spectrum. This assignment illustrates the measurements that helped Bohr develop his original quantum model, as well as some practical uses for this science by measuring the emission spectra for various gases that are common in lights. Skills Focus Observing, comparing and contrasting 1. Start Virtual Physical Science and select Atomic Emission Spectra from the list of assignments. The lab will open in the Quantum laboratory. A sample of gaseous sodium is on the lab bench in a sample tube and an alternating electric field of 300 V has been applied to cause the sodium gas to emit light. A spectrometer is on the right side of the lab bench and has been turned on. You can separate the light in an emission spectrum by using an optical prism or a diffraction grating. A spectrometer is an instrument designed to separate the emitted light into its component wavelengths. The detector window shows the output from the spectrometer. 2. Click on the Visible/Full switch in the detector window to change the output from the spectrometer to the visible spectrum. One spectral line is much more intense than all the others. Observing What is the color and wavelength (in nm) of this line? (To determine the wavelength, move the cursor over the line and read the wavelength in the x field at the bottom of the detector window. Look at the color at the top of the Spectrometer screen that corresponds to the peak wavelength.) Record your observations in the Data Table. Sodium vapor lights are becomming popular because of their energy efficiency and bright light. Astronomers are excited about cities changing from normal incandescent streetlights to sodium vapor streetlights because astronomers can easily filter out the peak at 589 nm and minimize light pollution. Incandescent lights emit light at all wavelengths of the visible spectrum and make filtering impractical. 118 Atomic Emission Spectra © Pearson Education, Inc. All rights reserved. Atomic Emission Spectra Procedure sx07CAGr8_VPhyLab_43.fm Page 119 Tuesday, August 14, 2007 7:21 AM Name ___________________________ Date ___________________ Class ____________ 3. You will test different types of gases to observe the colors and characteristics of different lights. To exchange gas samples, double-click or click and drag the Electric Field and place it on the stockroom counter, and double-click or click and drag the Gas (Na) sample tube and place it on the stockroom counter as well. You may have to click on the main laboratory window in order to move the items. 4. Enter the stockroom by clicking in the Stockroom. Click on the Gases samples on the top shelf. Click on the cylinder labeled Hg to replace the Na in the sample tube with mercury vapor. If you point to the gas sample tube with the cursor it should read Hg. 5. Return to the laboratory and drag the gas sample tube off the stockroom counter and place it in the middle of the table as indicated by the spotlight. Drag the Electric Field and place it on the gas sample tube. Carefully click the button just above the left zero on the Electric Field controller and change the voltage to 300 V. Turn on the Spectrometer by clicking on the red/green button. Atomic Emission Spectra 6. Comparing and Contrasting How does the spectrum for mercury look different from sodium? Record the color in the Data Table. Click on the Visible/Full switch in the detector window to change the output from the spectrometer to the full spectrum. You should see many more peaks in the ultraviolet range-to the left of the blue peak. The emitted light is not very bright for just the mercury vapor, but when scientists examined the full spectrum for mercury they saw what you just observed. There is an enormous emission in the ultraviolet region (UV). This light is sometimes called black light. You may have seen it with glow-in-the-dark displays. Scientists coat the inside of the glass tube of fluorescent light tubes with a compound that will absorb UV and emit the energy as visible light with all the colors of the visible spectrum. All colors together create white light, which is why fluorescent light tubes emit very white light. 7. Repeat steps 3–6 for the rest of the gases listed below in the table. Data Table © Pearson Education, Inc. All rights reserved. Gas Color of Light (highest peaks in visible Range) Sodium (Na) Mercury (Hg) Neon (Ne) Hydrogen (H2) Helium (He) 8. Observing Now you understand how neon lights can be different colors, depending on the type of gas inside the tubes. Designers can mix gases to create other colors or can color the tubes that the gas is in to add to the effect. What colors of neon lights have you seen? Atomic Emission Spectra 119 sx07CAGr8_VPhyLab_44.fm Page 120 Tuesday, August 21, 2007 12:42 PM Name ___________________________ Date ___________________ Class ____________ Lab 44: Plane Mirror Images Purpose To study the images observed in plane mirrors and to examine what a virtual image means Background Mirrors are everywhere. They are used to see images of ourselves, cars behind us, even to the stars. Plane mirrors are the most common type of mirrors. They have flat surfaces, and the image you see in them is exactly the same size as the original object. Skills Focus Predicting, observing, designing experiments Procedure 1. Start Virtual Physical Science and select Plane Mirror Images from the list of assignments. The lab will open in the Optics laboratory. 2. The laboratory will be set up with a candle on an optics table with a plane mirror in front of it. An eye will be set up at exactly the same distance from the mirror to be used as a detector, to look at the candle reflection in the mirror. You will observe the image of the candle from various distances and also observe the image of a beach ball to determine how images are changed in a mirror. 4. Mouse over the eye and a rotation control panel will appear. Rotate the eye to 90 degrees, so it is directly facing the candle. Sketch the candle as seen by directly looking at it on the optics table. Then rotate the eye to face towards the image from the mirror, at about 0 degrees. You can see the image of the candle in the Virtual Eye detector screen. Sketch the image of the candle that you see in the mirror. Plane Mirror Images Candle as seen from above Candle as seen in mirror 5. Click on the eye and drag it farther back on the table. How did the image change when you pulled back the viewing eye?_________________________ 120 Plane Mirror Images © Pearson Education, Inc. All rights reserved. 3. Predicting What do you think will happen to the image of the candle as the eyeball is pulled farther and farther back?__________________________ sx07CAGr8_VPhyLab_44.fm Page 121 Wednesday, August 22, 2007 6:51 AM Name ___________________________ Date ___________________ Class ____________ 6. The virtual eye does not have a lens in it, like human eyes do, which means that light isn’t focused down to a point, and you will not see variations in image size due to distance. The virtual eye is just a detector screen that light rays are reflected on to. The detector screen and the mirror are both bigger than the object, like a full body sized mirror. Since there is nothing to bend the light rays, they continue to travel in straight lines, no matter how far they are from the mirror. 7. Study how the image orientation is produced in a plane mirror. Click on the candle and drag it to the tray next to the beach ball. Click on the beach ball and bring it back to the optics table to where the candle in the same row of peg holes as the eye was. Use a colored pencil to draw in the colors of the ball in the correct order. Now drag the ball back to the position that the candle was in, so the eye can see the image of the ball from the mirror. The white images lines are displayed to help you find the sight line. Sketch the image of the ball as seen in the mirror below, making sure to correctly order the colors as you see them again. Beach ball as seen in 1st mirror Beach ball as seen in 2nd mirror 8. Pick up another mirror from the tray at the top of the table, and place it in a position so the light from the mirror can bounce on the second mirror too. You will probably need to rotate the mirror to face the direction of the bouncing light. The arrow head on the mirror indicates the reflective side. Now move the detector to be in line with the light bouncing off the second mirror. Rotate the eye as needed. You may need to adjust the orientation of your mirrors and detector so the sight line from the actual object is blocked. If you don’t, you will have multiple images displayed in the detector simultaneously and it might be hard to see which is the reflected image and which is the actual object. ___________________________________________ 9. Analyzing What observations did you make about the orientation of an image in a mirror? Where does the image appear to be? Plane Mirror Images © Pearson Education, Inc. All rights reserved. Beach ball as seen directly 10. Plane mirrors reflect what is called virtual images, images that seem to be inside the mirror or on the other side of the mirror, when actually no light can penetrate through the mirror. If you put a piece of paper behind the mirror, no image would show because the light isn’t really making it to that point. Devise and execute an experiment you could do to test this hypothesis. Plane Mirror Images 121 sx07CAGr8_VPhyLab_45.fm Page 122 Wednesday, August 15, 2007 7:39 AM Name ___________________________ Date ___________________ Class ____________ Lab 45: Concave Mirror Images Concave Mirror Images Purpose To study the images created in concave mirrors and to examine the relationship between the orientation of images and the location of the object in front of the mirror Background Not all mirrors are flat, like plane mirrors. Concave mirrors reflect light on the inside of the curved surface. Because of this inside curve, the image that’s seen changes depending on the distance between the object and the mirror. Flashlights and car headlights use concave mirrors because they require light to be focused into a narrow beam. Skills Focus Predicting, inferring, drawing conclusions Procedure 1. Start Virtual Physical Science and select Concave Mirror Images from the list of assignments. The lab will open in the Optics laboratory. 3. Predicting What do you think will happen to the image of the gnome as the object is pulled farther and farther back from the mirror? 4. Click on the gnome and drag it to the left of the detector, in the same row of peg holes. Mouse over the eye and a rotation control panel will appear. Rotate the eye to face the gnome and sketch it in the box below. Return the gnome to its original position and rotate the eye back to 5 degrees. Sketch the reflected image that you see in the mirror. Gnome as seen from above 122 Concave Mirror Images Gnome as seen in mirror © Pearson Education, Inc. All rights reserved. 2. The laboratory will be set up with a garden gnome on an optics table with a concave mirror in front of it. A detector, or virtual eye, is also placed on the table so it can look at the reflection in the mirror. You will observe the image of the gnome from various distances to determine how images are changed in a concave mirror. sx07CAGr8_VPhyLab_45.fm Page 123 Tuesday, August 14, 2007 8:13 AM Name ___________________________ Date ___________________ Class ____________ Concave Mirror Images 5. When light hits a concave mirror, it is all directed forward into a point in front of the mirror called a focal point. When the object you are looking at is farther away from the mirror than the focal point, the light from the object passes through the focal point and away at an angle, forming an upside down real image. When the object is between the mirror and the focal point, the image is called a virtual image, is right side up and seems to come from the other side of the mirror. Since light does not actually pass through the mirror, the image is referred to as a virtual image 6. Inferring What can you infer about the location of the object with respect to the focal point based on what you observed in the mirror? Are you observing a real or virtual image? Note the Height Factor displayed in the bottom of the detector screen. This is the magnifying factor of the image from the original size of the object. Record the value. _________________________________________________________________ 7. Click on the object and drag it a little farther back on the table. Observe the image of the gnome. You may need to rotate the mirror so the image line hits the detector. How did the image change when you pulled back the object? How have the height factor and orientation of the image changed? _________________________________________________________________ 8. Keep dragging the object farther and farther back and observe the size of the image as you pull back. What happens to the orientation of the image and the size of the image as you pull the object farther and farther back from the mirror? _________________________________________________________________ © Pearson Education, Inc. All rights reserved. _________________________________________________________________ 9. There is a certain point in front of the mirror through which all light is reflected. This is called the focal point. Light that reflects through that point bounces off the mirror in parallel rays and never intersects again. Observe what happens when you put an object in the focal point. Move the object towards the mirror from its current location, checking the image frequently. If you are farther away than the focal point, the image will be upside down, and then when you are past the focal point the image will be right side up, Keep moving it around that changing area to see if you can find the focal point. It may be easier to find the focal point if you move the gnome to the same line of pegs that the mirror is on. What happens to the image in that point? _________________________________________________________________ Concave Mirror Images 123 sx07CAGr8_VPhyLab_46.fm Page 124 Tuesday, August 14, 2007 8:24 AM Name ___________________________ Date ___________________ Class ____________ Lab 46: Convex Mirror Images Purpose To study the images created in convex mirrors and to measure the relationship between the apparent size of the images and the real distance to the object in front of the mirror Background Convex Mirror Images When you look at yourself in the back of a spoon or any other curved mirror where the mirror curves towards you, you are looking in a convex mirror. This type of mirrors reflects light on the outside of the curved surface. Convex mirrors are used to minimize the size of an object and are often seen in rear view mirrors on cars where it says, “Objects in mirror are closer than they appear.” Skills Focus Predicting, making judgments, controlling variables, measuring Procedure 1. Start Virtual Physical Science and select Convex Mirror Images from the list of assignments. The lab will open in the Optics laboratory. 3. Predicting What do you think will happen to the image of the candle that you see in the mirror as the object moves closer and closer to the mirror? 4. Mouse over the eye and a rotation panel will appear. Rotate the eye to face the candle at about 235 degrees. Sketch the object in the box below. Rotate the eye back towards the image reflected from the mirror at about 325 degrees. Sketch the image of the candle that you see in the mirror. Candle as seen directly 124 Convex Mirror Images Candle as seen in mirror © Pearson Education, Inc. All rights reserved. 2. The laboratory will be set up with a candle on an optics table with a convex mirror in front of it. A detector, or virtual eye, is also placed on the table so it can look at the candle reflection in the mirror. You will observe the image of the candle from various distances and also observe the image of a beach ball to determine how images are changed in a convex mirror. sx07CAGr8_VPhyLab_46.fm Page 125 Tuesday, August 14, 2007 8:24 AM Name ___________________________ Date ___________________ Class ____________ 5. When light hits a convex mirror, it appears that it is all directed forward into a point on the other side of the mirror called a focal point. Like a plane mirror, all of the images seem to diverge from the other side of the mirror, although really no light can go through the mirror. We will investigate the size of the images produced and their orientation. Since light does not actually pass through the mirror, the image is referred to as a virtual image. 6. Now you will click on the object and drag it closer to the mirror. Observe the image of the candle. How did the image change when you moved the object? _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ Convex Mirror Images 7. Keep pulling the object forward and observe the orientation and size of the image as you approach the mirror. What happens to the orientation and size of the image? Note the Height Factor displayed in the bottom of the detector screen. This is the magnifying factor of the image from the original size of the object. _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ 8. Rear view mirrors say “Objects in mirror are closer than they appear.” Investigate why they would say that. What properties have you observed that make objects seem farther away than they actually are? Think about how objects at a distance appear in normal plane mirrors. _________________________________________________________________ _________________________________________________________________ © Pearson Education, Inc. All rights reserved. _________________________________________________________________ 9. Controlling Variables Experiment with moving the object and keeping the eye position constant, and then keep the object position constant and move the eye position. Report your observations about size and orientation. _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ Convex Mirror Images 125 sx07CAGr8_VPhyLab_47.fm Page 126 Tuesday, August 14, 2007 9:03 AM Name ___________________________ Date ___________________ Class ____________ Lab 47: Looking at Images Problem To determine how an image is affected by the distance the object is from the lens Background How many movies have you seen in a theater this past month? Did you know that the film for the movie is placed in the projector upside down? Projectors have convex lenses inside which flip the image on the film and magnify it so it can be projected up on a screen a long distance away. Where there is a need to magnify smaller objects or shrink larger ones, convex lenses are often used. Convex lenses are used in applications such as in glasses for farsighted people, in cameras, and in lighthouses. Because of their unique uses, these lenses are found in many applications in the world. Skills Focus Predicting, observing, drawing conclusions Procedure 1. Start Virtual Physical Science and select Looking at Images from the list of assignments. The lab will open in the Optics laboratory. 3. Predicting What do you think will happen to the image of the candle that you see in the lens as the object moves closer and closer to the lens? _________________________________________________________________ 4. You will be placing the object at different distances from the lens, and then using the eye as a detector on the far side of the lens to find the location of the image produced by the lens. There is only one point at which an image is truly in focus. Turn off the autofocus feature in the detector screen by unchecking the Auto focus box. Move the detector eye until the image is in focus. In the data table record the distance from the lens to the image. Record the Height Factor displayed in the bottom of the detector screen. This is the magnifying factor of the image from the original size of the object. Repeat the experiment for all of the different distances of the object from the lens as shown in the Data Table. 126 Looking at Images © Pearson Education, Inc. All rights reserved. Looking at Images 2. The laboratory will be set up with a candle on an optics table with a convex lens in front of it. An eye will be on the other side of the lens so it can look at the image produced by the candle through the lens. You will observe the image of the candle from various distances to determine how images are changed in a convex mirror. sx07CAGr8_VPhyLab_47.fm Page 127 Tuesday, August 14, 2007 9:03 AM Name ___________________________ Date ___________________ Class ____________ Data Table Distance of object from lens (in.) 26 20 16 12 6 Distance of image from lens (in.) Inverted (yes/no) Image bigger or smaller than object? Height Factor 5. For all the experiments where the object is farther away than the focal point of the lens, the image is on the opposite side of the lens as the object. However, when the object is closer to the lens than the focal point, the image is actually on the same side of the lens as the object. A common example of this is with a magnifying glass being used to magnify something. You look in the magnifying glass and see the image of the object bigger than it actually is, on the same side of the lens as the actual object. Predicting What do you think an object at the focal point of the lens will produce? _________________________________________________________________ 6. Move the object to the focal point of the lens, which is located at 8 in. (or 4 pins from the lens). Sketch the image and record the distance. Did you get what you predicted? What is a characteristic of convex lenses that you observe here? _________________________________________________________________ Looking at Images Analyze and Conclude © Pearson Education, Inc. All rights reserved. 7. When objects are very far away, what does the image look like? _________________________________________________________________ 8. What happens when the object is located between the focal point and the lens? _________________________________________________________________ 9. If you didn’t know the focal point of a convex lens, how might you be able to discover it? _________________________________________________________________ Looking at Images 127 sx07CAGr8_VPhyLab_48.fm Page 128 Tuesday, August 14, 2007 9:21 AM Name ___________________________ Date ___________________ Class ____________ Lab 48: Ohm’s Law Problem To develop the relationship among voltage, current, and resistance by manipulating these variables in electric circuits and examining the effects Background The unit for resistance—the ohm—is named after Georg Ohm, a German scientist. Ohm hypothesized that resistance reduces the voltage, or the potential difference between different parts of an electric field. He published his research in 1826, but his findings were not accepted immediately. Ohm found the mathematical relationship among voltage, current, and resistance, which is widely used today. Skills Focus Controlling variables, drawing conclusions, understanding models Procedure 1. Start Virtual Physical Science and select Ohm’s Laws from the list of assignments. The lab will open in the Circuits laboratory. 3. First learn about the components that you will be using. Check the value of the voltage source labeled on the battery pack above the breadboard. Record your answer in Data Table 1. Do the same for the resistor component by looking at the schematic on the engineering paper to the left or by mousing over the resistor. Ohm’s Law 4. An ammeter is connected to the resistor to measure the current (amps) that is going through the circuit. The ammeter is part of the yellow multimeter on the top right side of the table. Record the current shown on the ammeter in the table. 5. To understand the relationship among these three variables, you will hold one constant and change another to see the effect. Start with controlling the voltage variable. This means you won’t change the voltage as you adjust the other variables. Change the resistance of the resistor by right clicking on the resistor and entering a value of 10. Record the new current through the circuit. Continue changing the resistor as indicated in the table and record the current and voltage in each case. 128 Ohm’s Law © Pearson Education, Inc. All rights reserved. 2. The laboratory will be setup with a voltage source and a resistor attached to the breadboard. A breadboard is a reusable circuit board, which allows you to connect components of a circuit by plugging the pieces into the board and knowing which parts of the board are internally connected to each other. The voltage source will be turned on and the resistor will be attached to the source. sx07CAGr8_VPhyLab_48.fm Page 129 Wednesday, August 15, 2007 7:42 AM Name ___________________________ Date ___________________ Class ____________ Data Table 1 Resistance (R) Voltage (V) 1 1.5 10 1.5 100 1.5 1000 1.5 10000 1.5 Current (A) 6. Now you will change the voltage and control the resistance to see how this affects the measured current. Start with a 100 ohm resistor and change the voltage source through all of the allowable voltages. Record your data in Data Table 2. Data Table 2 Resistance (R) Voltage (V) 100 1.5 100 3 100 4.5 100 9 100 12 Current (A) 7. What happened to the current in the circuit when you increased the resistance? 8. What does it mean if increasing the resistance affects the current—what is going on electrically? What could happen if the resistance is increased too much? 9. What happened to the current in the circuit when you increased the voltage in the circuit? 10. A circuit can be modeled like a flowing river. What would represent voltage sources, resistors, and current in the river example? Think about how they each affect the flow of the river. Ohm’s Law © Pearson Education, Inc. All rights reserved. Analyze and Conclude 11. We can represent the current as I = V/R. Does this equation model your findings? Support your answer from your data. Ohm’s Law 129 sx07CAGr8_VPhyLab_49.fm Page 130 Monday, August 20, 2007 1:02 PM Name ___________________________ Date ___________________ Class ____________ Lab 49: Circuit Diagrams Circuit Diagrams Problem Understand the meanings of the different symbols in circuit diagrams and learn how to create and use them Background An electric circuit diagram is a symbolic drawing showing the elements of an electric circuit. The diagrams are drawn to make it easy to see the whole path through which a current is flowing, through all of the different parts of a circuit. Circuit diagrams can look like very complex mazes of wires and symbols. However, if you learn to break them down piece by piece, they will make sense. Knowing how to interpret circuit diagrams will help you understand how your house is wired and how simple electrical devices like flashlights and blow dryers work. Skills Focus Understanding procedures, relating concepts Procedure 1. Start Virtual Physical Science and select Circuit Diagrams from the list of assignments. The lab will open in the Circuits laboratory. 3. You will first build a circuit with a light bulb and a battery in series. You will be drawing the diagram on the pad of paper, which will automatically pull those actual elements out onto the breadboard and you will see the circuit being built as you draw it. a. On the pad of paper, grab and drag battery symbol and place it on the right hand side of the paper. The battery symbol has two small parallel lines labeled + and - and has two lines representing wires at right angles with the parallel lines coming out from the sides. b. Now find a light bulb symbol and place it on the pad to the left of the battery. This looks like an x in the middle of a circle. c. Connect one end of the light bulb to positive terminal of the battery by clicking and dragging the blue spot on the resistor to the green spot on the positive end of the battery. d. Attach the other end of the light bulb to the negative end of the battery. e. Now click the number above the light bulb and change its value to 100w. 130 Circuit Diagrams © Pearson Education, Inc. All rights reserved. 2. The laboratory will be set up with all of the components in the boxes at the bottom of the table. Nothing will be on the breadboard, which is the board with holes in the middle of the table that we use to build circuits on. You will need to follow the instructions below to determine how to place the components on the diagram. You will also check to see if you correctly placed the components. sx07CAGr8_VPhyLab_49.fm Page 131 Monday, August 20, 2007 1:02 PM Name ___________________________ Date ___________________ Class ____________ f. Increase the voltage from the battery by clicking on the arrow next to the power button on the battery controller at the top. Circuit Diagrams g. You should see the light bulb assembled on the breadboard. If you connected your wires correctly, then the light bulb should be lit. 4. You will now build a circuit with a light bulb and an oscillating power source. a. On the pad of paper, grab and drag the function generator symbol and place it on the right hand side of the paper. The function generator symbol is a circle with a sine wave symbol inside and has two lines representing wires coming out from the sides. b. Now place a light bulb symbol on the pad to the right of the function generator. c. Connect one end of the light bulb to the positive terminal of the function generator as you did in Step 3c above. d. Attach the other end of the light bulb to the negative end of the function generator. © Pearson Education, Inc. All rights reserved. e. You should see the light bulb assembled on the breadboard. If you connected your wires correctly, then the light bulb should be lit. You will probably need to adjust the frequency on the function generator until you see the light bulb fade on and off as the voltage gradually increases and decreases. At what frequency do you see the light bulb blinking? 5. Now play around with building a circuit with the different batteries, light bulbs, capacitors, and inductors available. You will want to make sure your light bulb will light, but you can wire it however you want to. You must have 4 elements in your circuit. Draw your circuit diagram in the box below and describe what happens when you connect the circuit. For example, does your bulb flash, does it blow out, does it start out lit, then turn off? You might need to change the amount of resistance, capacitance, and inductance from the default values. You do this by clicking on the label for each component and entering the amount. Here are some sample values if you need suggestions on component values: R1 100 , C1 0.1F, L1 .001H. Circuit Diagrams 131 sx07CAGr8_VPhyLab_49.fm Page 132 Monday, August 20, 2007 1:02 PM Date ___________________ Class ____________ Circuit Diagrams Name ___________________________ Circuit diagram Describing What happens in your circuit? __________________________________________________________________ __________________________________________________________________ Analyze and Conclude 6. Some people think it is easier to build circuits just by moving around the components on the breadboard. However, as you have probably seen, that can get really messy with wires connecting all over the place. What is the advantage to planning circuits with a diagram? __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ 8. When would it be important to have a circuit diagram? __________________________________________________________________ __________________________________________________________________ 9. In your life, where have you used something similar to a circuit diagram? __________________________________________________________________ __________________________________________________________________ 132 Circuit Diagrams © Pearson Education, Inc. All rights reserved. 7. Describe how you can tell where the current is flowing in a circuit diagram. __________________________________________________________________ sx07CAGr8_VPhyLab_50.fm Page 133 Tuesday, August 14, 2007 9:29 AM Name ___________________________ Date ___________________ Class ____________ Lab 50: Building Electrical Circuits Problem To construct series and parallel circuits and measure the voltage and current through each type of circuit Background Building Electrical Circuits Electronic devices like your computer or video game system require a certain amount of electrical current to operate. The amount of current necessary can be determined easily by the principles of electronics. If we obey these principles the devices will work just fine; if not, they won't function properly. Before building an electrical circuit for a device, you must first know all about the device you are trying to build. You need to know if you can use series or parallel connections to control the current for the device. As you will learn in this lab, there are benefits to both kinds of connections. In this lab you will study each type and learn the different applications of series and parallel circuits. Skills Focus Interpreting data, drawing conclusions, developing hypothesis, relating differences Procedure © Pearson Education, Inc. All rights reserved. 1. Start Virtual Physical Science and select Building Electrical Circuits from the list of assignments. The lab will open in the Circuits laboratory. 2. The laboratory will be set up with all of the components in the storage compartments at the bottom of the screen. Nothing will be on the breadboard. You will need to follow the instructions below to determine how to place the components on the diagram. Remember that a breadboard consists of rows and columns that are connected to each other by metal strips on the under side. The holes in the columns between the red and blue strips are connected only to the other holes in their particular column. The top column, by the red strip is for the + voltage source and the other column is for the - voltage source. The holes in the rows in the middle of the board are connected to each other and are labeled 1 through 25 with two separate sets of rows. That means that all of the holes labeled a–e in the row labeled 1 are connected to each other, as are all the a–e holes in row 2, but those rows aren’t connected to each other. Follow the instructions below to build the appropriate circuits. 3. You will first build a simple DC light bulb series circuit on the breadboard. You will build it in phases and examine each phase as you go along. Building Electrical Circuits 133 sx07CAGr8_VPhyLab_50.fm Page 134 Wednesday, August 15, 2007 7:43 AM Name ___________________________ Date ___________________ Class ____________ Phase 1: One Light Bulb a. Grab and drag out a small light bulb and place it on the breadboard with one prong in hole 10b and place the other prong in hole 15b. Notice that the wires connecting the voltage source to the breadboard. One wire goes to the positive input column and one goes to the negative input thus completing the circuit. You need to bring a new wire from the box and connect it from the positive red column to the row where your light bulb is attached, and place it into 1a. Bring another wire from 15a over to the negative blue column. b. Record in the table if the light bulb lights or not. It should light, so rewire the circuit if you need to, to make sure everything connects. Building Electrical Circuits Phase 2: Two Light Bulbs in series c. Bring out another small light bulb and connect it in series with the first light bulb by placing one prong of the second light bulb into hole 15c and the other into hole 20c. Then move the wire connecting the negative terminal from 15a to 20a so that the circuit is complete. d. Record in the table if both light bulbs light and rate their brightness relative to how bright the single light bulb was. Phase 3: Three Light Bulbs in series e. Now add another light bulb from hole 20d to 25d. f. Move the negative terminal wire from hole 25a to 25a so the circuit is complete. g. Record in the table if all three light bulbs light and rate their brightness again. h. Pull out one of the bulbs, but don’t change any of the other wires and record what happens. Data Table 1: Series Circuit Phases Lights? Brightness Two Light Bulbs Three Light Bulbs 4. You will now build a simple parallel DC circuit. You will build it in phases and examine each phase as you go along. Phase 1: Two Light Bulbs in parallel a. Remove the third light bulb and place it back into its box. b. Move the second light bulb to be in holes 10e and 15e respectively. 134 Building Electrical Circuits © Pearson Education, Inc. All rights reserved. One Light Bulb sx07CAGr8_VPhyLab_50.fm Page 135 Tuesday, August 14, 2007 9:29 AM Name ___________________________ Date ___________________ Class ____________ c. Move the negative terminal wire from 25a to be in 15a so that the circuit will be complete. d. Record in the table if both light bulbs light and rate their relative brightness as compared to just one light bulb. Phase 2: Three Light Bulbs in parallel e. Now add another light bulb into holes 15d and 10d respectively. f. Record in the table if all three light bulbs light and rate their relative brightness as compared to just one light bulb and compared to the 2 light bulbs. g. Pull out one of the bulbs, but don't change any of the other wires and record what happens. Data Table 2: Parallel Circuit Lights? Building Electrical Circuits Resistor Number Brightness Two Light Bulbs Three Light Bulbs Analyze and Conclude 5. Analyze In the series circuit what characteristic was common throughout the experiment? What changed as you added more light bulbs? __________________________________________________________________ __________________________________________________________________ 6. Analyze In the parallel circuit what characteristic was the same throughout the experiment? __________________________________________________________________ © Pearson Education, Inc. All rights reserved. __________________________________________________________________ 7. Conclude From questions 5 and 6, why would knowing these characteristics of circuits be important in designing electrical circuits? __________________________________________________________________ __________________________________________________________________ 8. If you wanted to check to see if a set of Christmas lights were connected in series or parallel how could you do this? __________________________________________________________________ __________________________________________________________________ Building Electrical Circuits 135 sx07CAGr8_VPhyLab_50.fm Page 136 Tuesday, August 14, 2007 9:29 AM Name ___________________________ Date ___________________ Class ____________ 9. Name two examples of series circuits. Name one example of parallel circuit. __________________________________________________________________ __________________________________________________________________ 10. Extension Activity Connect two light bulbs in series with a power source. Then add a light bulb in parallel with the first light bulb. What happens to the brightness of the bulb that is in series with the two parallel bulbs? What happens when you have 3 bulbs in parallel and then the one bulb in series with that whole combination? Why do you think the brightness changes as you see? __________________________________________________________________ Building Electrical Circuits __________________________________________________________________ © Pearson Education, Inc. All rights reserved. 136 Building Electrical Circuits sx07CAGr8_VPhyLab_51.fm Page 137 Tuesday, August 14, 2007 9:41 AM Name ___________________________ Date ___________________ Class ____________ Lab 51: Making Observations of Our Solar System Purpose To investigate the motion of Earth and the other objects in the solar system Background It’s hard to appreciate the magnitude or size of the solar system. The masses of the planets and other objects, the sizes of their orbits, and the speeds at which they travel are amazing. In order to gain some understanding, you can relate the motion of the objects to things you can understand, for example, the time it takes Earth to go around the sun (one Earth year). Then you can compare other objects to Earth. In this assignment, you will make qualitative observations about the solar system. Skills Focus Observing, predicting, drawing conclusions Procedure 1. Start Virtual Physical Science. Select Making Observations of Our Solar System from the list of assignments. The lab will open in the Mechanics laboratory. Making Observations of Our Solar System © Pearson Education, Inc. All rights reserved. 2. The laboratory is set up in the Solar System View with the sun in the middle. The inner planets (not to scale) are in their orbits. The outer planets, Pluto, and a comet are in the transfer table. You can click on the Start button to see the inner planets (Mercury, Venus, Earth and Mars) begin to orbit in their individual paths around the sun. Click Pause when you have finished observing. Click Reset. 3. Observing The planets move in their orbits at different speeds. The time it takes a planet to make one trip around the sun is called the period of its orbit. The Time display gives the current time for the solar system in year:day format. The experiment starts on the current day of the year which is shown in the Time display. Choose a planet to watch first. Click the Start button and watch the planet. When the planet returns to the start of its orbit, click Pause. In the second column of the table on the next page, record the Time display at the end of one orbit. You can speed up or slow down the process using the Time Acceleration buttons. To calculate the period of one orbit, first subtract the initial year at the beginning of the orbit from the year after one orbit. Then divide the number of days by 365. This is a fraction of an Earth year. Add the whole number of years to the fraction to get the total period. Record this number in the last column of the table. Click Reset and repeat the procedure for each remaining object. To find the periods of the outer planets, Pluto, and the comet, drag them from the transfer table to the work area. Making Observations of Our Solar System 137 sx07CAGr8_VPhyLab_51.fm Page 138 Tuesday, August 14, 2007 9:41 AM Name ___________________________ Object Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune Pluto Comet Date ___________________ Time Display at the End of One Orbit (year:day) Class ____________ Period of One Orbit (in Earth years) 4. Observing What general difference do you observe between the inner planets and the outer planets (those farther away from the sun than Mars)? What is different about the orbit of Pluto? What differences do you observe about the orbit of the comet? __________________________________________________________________ __________________________________________________________________ 5. Predicting From your view of the solar system, it looks as if the comet could collide with the other objects. Why do you think this doesn’t happen very often? __________________________________________________________________ __________________________________________________________________ 6. Drawing Conclusions Change the view of the solar system by clicking on the Parallel View button. You can now view the motion of the objects from the side view or the plane of the orbits. Notice that most of the objects move in the same plane, but the orbits of Pluto and the comet are tilted at an angle from the plane of the planets. How does this support your answer in Step 5? __________________________________________________________________ __________________________________________________________________ 7. Observing Change the view that you are looking at by clicking on the Object View button on the side. Click on each object to observe its moons. Only the major moons of each object are displayed. Which objects have the most moons? Are there any objects that do not have moons orbiting them? __________________________________________________________________ 8. Note one thing you have observed about the solar system that you did not know before. __________________________________________________________________ 138 Making Observations of Our Solar System © Pearson Education, Inc. All rights reserved. Making Observations of Our Solar System __________________________________________________________________ sx07CAGr8_VPhyLab_52.fm Page 139 Tuesday, August 14, 2007 9:48 AM Name ___________________________ Date ___________________ Class ____________ Lab 52: Tracking the Phases of the Moon Purpose To investigate the phases of the moon Background Sometimes, on cloudless nights, you might go outside and enjoy the light of the sun by its reflection off the surface of the moon. Probably you have noticed that on different nights the moon has a different shape. Its shape varies from full moon (fully round) to new moon (no light) depending on the time of the month. The shape of the illuminated part of the moon at any time of the month is called the phase of the moon. In this assignment you will discover why the moon has different phases. Skills focus Predicting, observing, drawing conclusions Procedure 1. Start Virtual Physical Science. Select Tracking the Phases of the Moon from the list of assignments. The lab will open in the Mechanics laboratory. 2. The virtual laboratory is set up in the Top Planet View. In this view you can look at the Earth-Moon system. Earth is in the middle of the screen. The sun’s rays are coming from the top of the screen. 3. Click the Start button and watch as the moon orbits Earth. Use the Time Acceleration buttons to speed time up and slow time down. Observe the motion of the moon for one month (30 days). Predicting What do you think causes the phases of the moon? _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ 4. Click on the Reset button to reset the experiment. Repeat the experiment to make specific observations. This is approximately the way things are oriented on the current day. On Diagram 1a, sketch what the moon looks like from above. Click on the Inside Object View button to observe the moon from Earth. Sketch what you see in Diagram 1b. Use the Rotate Around Object button if the moon is not in the viewing area, until you see the moon. Tracking the Phases of the Moon Tracking the Phases of the Moon © Pearson Education, Inc. All rights reserved. _________________________________________________________________ 139 sx07CAGr8_VPhyLab_52.fm Page 140 Tuesday, August 14, 2007 9:48 AM Name ___________________________ Date ___________________ Class ____________ Diagram 1 a.—View from above b.—View from Earth Moon Sun 5. Return to the Top Object View and advance the time to 7 days. Observe what the moon looks like. On Diagram 2a, sketch what the moon looks like from above. Click on the Inside Object View button to observe the moon from Earth. Sketch what you see in Diagram 2b. Diagram 2 a.—View from above b.—View from Earth Moon Sun Diagram 3 Tracking the Phases of the Moon a.—View from above b.—View from Earth Moon Sun 140 Tracking the Phases of the Moon © Pearson Education, Inc. All rights reserved. 6. Return to the Top Object View and advance the time to 7 more days. Observe what the moon looks like. On Diagram 3a, sketch what the moon looks like from above. Then click on the Inside Object View button to observe the moon from Earth. Sketch what you see in Diagram 3b. sx07CAGr8_VPhyLab_52.fm Page 141 Tuesday, August 14, 2007 9:48 AM Name ___________________________ Date ___________________ Class ____________ 7. Return to the Top Object View and advance the time 7 more days. Observe what the moon looks like. On Diagram 4a, sketch what the moon looks like from above. Then click on the Inside Object View button to observe the moon from Earth. Sketch what you see in Diagram 4b. Diagram 4 a.—View from above b.—View from Earth Moon Sun 8. Return to the Top Object View and advance the time to 8 more days. Observe what the moon looks like. On Diagram 5a, sketch what the moon looks like from above. Click on the Inside Object View button to observe the moon from Earth. Sketch what you see in Diagram 5b. Diagram 5 Tracking the Phases of the Moon © Pearson Education, Inc. All rights reserved. a.—View from above b.—View from Earth Moon Sun Tracking the Phases of the Moon 141 sx07CAGr8_VPhyLab_52.fm Page 142 Tuesday, August 14, 2007 9:48 AM Name ___________________________ Date ___________________ Class ____________ 9. In Diagram 6 the moon is shown in four different locations around Earth relative to Earth. These locations correspond to various days in a month. Indicate approximately which days these correspond to what you have examined. 10. Remember what you observed in Steps 4–8. Half of the moon is always illuminated by the sun. Sketch this in Diagram 6. Diagram 6 Analyze and Conclude 1. Drawing Conclusions Use your sketches of the moon at different times of the month to explain why the moon has different phases. __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ Tracking the Phases of the Moon 142 Tracking the Phases of the Moon © Pearson Education, Inc. All rights reserved. 2. Was your prediction about the cause of the phases of the moon correct? Why or why not? __________________________________________________________________ sx07CAGr8_VPhyLab_53.fm Page 143 Tuesday, August 14, 2007 9:50 AM Name ___________________________ Date ___________________ Class ____________ Measuring the Orbital Speed of the Planets Lab 53: Measuring the Orbital Speed of the Planets Purpose To determine how fast Earth and the other planets are moving Background When you are traveling fast in a car, objects along the roadside appear to move by quickly. But when you travel in an airplane, objects that you see below seem to move more slowly, even though the plane is moving faster than the car. Why is this? Every day Earth turns around or rotates once on its axis. This is what causes the sun to move across the sky. But besides rotating, Earth is also moving in its orbit around the sun. This motion takes a year, but you don’t even notice it. In this assignment you will determine the speed of Earth in its orbit and come to appreciate how fast you are actually moving. Skills Focus Observing, predicting, calculating, drawing conclusions, relating cause and effect Procedure © Pearson Education, Inc. All rights reserved. 1. Start Virtual Physical Science. Select Measuring the Orbital Speed of the Planets from the list of assignments. The lab will open in the Mechanics laboratory. 2. The laboratory is set up in the Solar System View with the sun in the middle. You will see the inner planets (not to scale) in their orbits. Click on the Start button. The planets will begin to move in their orbits around the sun. Click Pause when you have finished observing. Each planet moves at a different speed in its orbit. You can calculate their speeds by using the formula: Speed Distance ------------------Time Predicting Approximately how fast do you think Earth is traveling in its orbit? __________________________________________________________________ 3. You will first measure the distance from the sun to each planet in the solar system. A planet’s distance from the sun is called the radius of orbit. Click on each planet and record, in the table below, the radial distance from the sun. This distance is displayed below the experiment window where it has a value for r. You will use the radius of orbit to estimate the circumference or length of each planet’s orbit. The displayed radius is the radius at the given day, which could be larger or smaller than the average radius. The planets’ orbits are ellipses rather than circles, but a good approximation can be made by considering them to be circles. Recall that the formula for the circumference of a circle is C2πR where C is the circumference and R is the radius. Calculate the circumference of each planet’s orbit and record it in the table. Measuring the Orbital Speed of the Planets 143 sx07CAGr8_VPhyLab_53.fm Page 144 Tuesday, August 14, 2007 9:50 AM Measuring the Orbital Speed of the Planets Name ___________________________ Date ___________________ Class ____________ 4. Observing The amount of time it takes for each planet to travel once around its orbit is called its period. Click the Reset button to return all planets to their original positions. To record the period of each planet, click the Start button. Watch one of the planets. Click Pause when the planet returns to the position it started from. To calculate the period in years, divide the number of days elapsed by 365. This is a fraction of a year. Add the whole number of years that passed to this fraction to get the total period. Record in the table the time it took to orbit. Click Reset to reset the time clock and repeat the experiment for each planet. You will want to accelerate time in the time window by using the Time Acceleration buttons. Add the remaining planets, as well as Pluto and the comet, from the tray to the work area. Collect the same data for these objects too. Table Object Radius of Orbit (AU) Circumference of Orbit (AU) Period (years) Orbital Speed (AU/year) Orbital Speed (miles/ hour) Mercury Venus Earth Mars Jupiter Saturn Neptune Pluto Comet Analyze and Conclude 1. Calculating Calculate the orbital speed of each planet by dividing the distance it travels in its orbit by the period. The units of your answer should be AU/year. Record your answers in the table. 2. Calculating Multiply the orbital speed you just calculated by 10604. This changes a speed in AU/year to miles/hour. (This conversion works because 1 AU/year 10,604 miles/hour.) Record your answers in the table. Is this fast? __________________________________________________________________ 3. Drawing Conclusions Why don’t you feel as if you are moving this fast? __________________________________________________________________ 4. Relating Cause and Effect If Earth is really going as fast as you calculated it is, why doesn’t the planet fly out of its orbit into space? __________________________________________________________________ 144 Measuring the Orbital Speed of the Planets © Pearson Education, Inc. All rights reserved. Uranus sx07CAGr8_VPhyLab_54.fm Page 145 Tuesday, August 14, 2007 9:52 AM Name ___________________________ Date ___________________ Class ____________ Lab 54: How Strong is Gravity? Problem To compare the gravitational forces on different planets and moons in the solar system Background The English scientist Isaac Newton realized that gravity acts everywhere in the universe, not just on Earth. Gravity is the force that makes an apple or any other object fall to the ground. It is the force that holds you firmly on Earth’s surface so that you don’t fly off into space. It is the force that keeps the moon orbiting around Earth. It is the force that keeps all the planets in our solar system orbiting around the sun. In this lab you will visit some of the planets or moons in the solar system and observe how the acceleration due to gravity differs depending on where you are. How Strong is Gravity? Skills Focus Interpreting data, graphing, drawing conclusions, applying concepts Procedure 1. Start Virtual Physical Science. Select How Strong is Gravity? from the list of assignments. The lab opens in the Mechanics laboratory. © Pearson Education, Inc. All rights reserved. 2. The laboratory is set up with a ball at the top of the experiment window, 30 m above the surface. This is about as high as a nine story building. Gravity, which is set the same as on Earth, will pull the ball downward. You will observe how long it takes the ball to fall to the ground. The mass of the ball is 1 kg. 3. Click on the Lab Book to open it. Click on the red Recording button to start recording data. Start the experiment by clicking on the Start button and observe what happens. When the ball reaches the bottom, the experiment will stop and you should see a link appear in the Lab Book. This contains the velocity versus time data for the falling ball. 4. Click the Reset button to reset the experiment. Use the Gravity tab under the Parameters Palette to select a different planet, which will have a different gravity. Repeat Step 3 to record the velocity of the ball as it falls. Do this on four different planets or moons. Try a big planet such as Jupiter and a small body such as Earth’s moon. How Strong is Gravity? 145 sx07CAGr8_VPhyLab_54.fm Page 146 Tuesday, August 14, 2007 9:52 AM Name ___________________________ Date ___________________ Class ____________ 5. Use the data in each of the data links in the Lab Book to fill in the tables below. You will need the speeds of the balls, so open the velocity versus time links for each planet or moon. In each of the tables, record the speed (make the velocity positive) at the nearest time interval for the first three seconds. Table 1 Planet Earth Time (s) Speed (m/s) 0 0.5 1.0 1.5 How Strong is Gravity? 2.0 2.5 3.0 Table 2 Table 3 Planet Time (s) Planet Speed (m/s) Time (s) 0 0.5 0.5 1.0 1.0 1.5 1.5 2.0 2.0 2.5 2.5 3.0 3.0 Table 4 Table 5 Planet Time (s) © Pearson Education, Inc. All rights reserved. 0 Speed (m/s) Planet Speed (m/s) Time (s) 0 0 0.5 0.5 1.0 1.0 1.5 1.5 2.0 2.0 2.5 2.5 3.0 3.0 146 How Strong is Gravity? Speed (m/s) sx07CAGr8_VPhyLab_54.fm Page 147 Tuesday, August 14, 2007 9:52 AM Name ___________________________ Date ___________________ Class ____________ Analyze and Conclude 1. Graphing For each experiment, use the data in the tables to draw a speed versus time graph on the grid below. Label the horizontal axis Time (s) and the vertical axis Speed (m/s). Scale the graph to fit your data. The first data point will always be (0 s, 0 m/s). Connect the data points using different colored pencils for each planet or moon. Label each line with the name of the planet or moon. How Strong is Gravity? 2. Interpreting Data How does the speed at which the balls fall vary from planet to planet? __________________________________________________________________ © Pearson Education, Inc. All rights reserved. On which planet did the ball fall the fastest? On which planet did the ball fall the slowest? __________________________________________________________________ 3. Applying Concepts What does the constant slope of each of the graphs tell you about the motion of the ball? __________________________________________________________________ 4. Drawing Conclusions Which planet has the strongest gravity? __________________________________________________________________ Going Further 5. Calculate the gravitational acceleration of the planet that you said has the strongest gravity. Remember that the slope of a speed or velocity graph is the acceleration. (Slope = Rise/Run, Acceleration = Change in velocity/Change in time). Earth’s gravitational acceleration is 9.8 m/s/s. How much stronger is gravity on your planet than on Earth? __________________________________________________________________ __________________________________________________________________ How Strong is Gravity? 147 sx07CAGr8_VPhyLab_55.fm Page 148 Tuesday, August 14, 2007 9:59 AM Name ___________________________ Date ___________________ Class ____________ Lab 55: Why Pluto is Not a Planet Purpose To learn why scientists reclassified Pluto Background According to the new definition accepted by astronomers, a true planet is an object that orbits the sun and is large enough to have become round due to the force of its own gravity. In addition, a planet has to be bigger than all the other objects around its orbit. Pluto has been demoted from a planet to a “dwarf planet” because it does not dominate in the area around its orbit. Charon, its large "moon," is only about half the size of Pluto, while all the true planets are far larger than their moons. Skills Focus Observation, Interpreting observations, Drawing comparisons, Ranking Procedure 1. Start Virtual Physical Science and select Why Pluto is Not a Planet from the list of assignments. The lab will open in the Mechanics laboratory. The laboratory will be set up in a simulation of the solar system, zoomed down to where you can see all the planets of the solar system and Pluto. 3. Find the mass of Mercury. On the Parameters Palette click on the icon of Mercury. Record the mass of Mercury in table 1. 4. Find the Orbital Inclination. The inclination is the amount of tilt that the orbit of the planet, including Pluto, is tilted with respect to the orbit of the Earth. So, if the object has an inclination of 7°, then its orbit is tilted by 7° from the orbit of Earth. In the Object section of the Parameters Palette find the inclination of Mercury and record it in table 1. 5. Find the average orbital radius, which is the average distance that the planet (including Pluto) orbits away from the Sun. To determine an average orbital radius, choose four different locations in the orbit and record the distance from the Sun. First click on a planet or Pluto in the Solar System View to have the data displayed in the data table below the viewing screen. Find the radius labeled r. This is the radius from the Sun. Record this radius in Table 2 Location 1. Click Start to start the object’s orbiting and Pause when the object is in a different part of its orbit and record the radius there. You will probably want to remove some of the outer planets and Pluto to the tray at the top of the screen, so that you can see the orbits of the inner planets better. It may also help if you accelerate 148 Why Pluto is Not a Planet © Pearson Education, Inc. All rights reserved. Why Pluto is Not a Planet 2. Compare the planets using the information gathered from the Parameters Palette and from the data displayed at the bottom of the screen. Fill in the table with the appropriate information. The following instructions will show how to gather the information. Repeat for all the planets and Pluto. sx07CAGr8_VPhyLab_55.fm Page 149 Tuesday, August 14, 2007 9:59 AM Name ___________________________ Date ___________________ Class ____________ time in the time control panel at the bottom left of the screen, to make the time pass faster in the orbits. Click the + sign to make time go faster, and – to slow it down. Choose three other locations in each orbit and record these radii in Table 2. 6. Find the average of those four radii by adding them and then dividing by four (the number of locations you choose). Use Table 2 to record the four different radii. Then record your average in the Table 1. Table 1: Observation Table Object Mass Inclination Average Orbital Object Radius Radius (km) Mercury 2.44 103 Venus 6.05 103 Earth 6.37 103 Mars 3.40 103 Jupiter 7.15 104 Saturn 6.03 104 Uranus 2.56 104 Neptune 2.48 104 Pluto 1.20 103 Table 2: Orbital Radius Object Location 1 Location 2 Location 3 Location 4 Why Pluto is Not a Planet Mercury Venus Earth Mars © Pearson Education, Inc. All rights reserved. Jupiter Saturn Uranus Neptune Pluto Analyze and Conclude 7. Ranking Using the data collected in the Observation Table, rank the planets and Pluto from smallest to largest. Why Pluto is Not a Planet 149 sx07CAGr8_VPhyLab_55.fm Page 150 Tuesday, August 14, 2007 9:59 AM Name ___________________________ Date ___________________ Class ____________ Object Radius Smallest -------- -------- -------- Medium ------- -------- --------- Largest ------- -------- --------- Largest ------- -------- --------- Largest Mass Smallest -------- -------- -------- Medium Inclination Smallest -------- -------- -------- Medium 8. Drawing conclusions How does Pluto’s orbital radius compare with those of the planets’? _________________________________________________________________ 9. According to the ranking charts above, explain why reclassifying Pluto according to these variables is a good decision. _________________________________________________________________ 10. Click on different planets and use the Object View button (concentric circles with an arrow pointing in) to zoom down onto each planet and its moons. Compare the motion and size of the other planets and their moons to Pluto and its moon Charon. How do they compare? How do they differ? _________________________________________________________________ _________________________________________________________________ 11. Developing Opinion Do you agree or disagree with the reclassification? Use data observation to explain your answer. _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ 150 Why Pluto is Not a Planet © Pearson Education, Inc. All rights reserved. Why Pluto is Not a Planet _________________________________________________________________ sx07CAGr8_VPhyLab_Answer.fm Page 151 Friday, September 7, 2007 7:00 AM Answers Lab 1—Introduction to Scientific Inquiry 1. A sample question might be: How does the volume of a balloon change when the temperature changes? Analyze and Conclude 1. The balloon got larger as the temperature was increased. 2. A sample hypothesis might be: Increasing the temperature will increase the volume of the balloon. 2. Temperature is on the horizontal axis and volume on the vertical axis. The graph is a straight line starting at 100°C and 1531 cm3 and slopes upward to the right. 3. Begin with a balloon filled with gas at a certain temperature. Measure the volume and then increase the temperature. Compare the volume and temperature at the higher temperature with the original measurements to determine the effect of changing temperature. Temperature (°C); Volume (cm3); About 3000 cm3 The volume should be approximately 5200 cm3 when the temperature is 1000°C. Temperature; Volume Temperature (°C) Volume 3. A sample answer might be: The hypothesis stated that volume would increase as temperature increased. The data shows that the volume increases as the temperature increases. The graph confirms this conclusion. The hypothesis was correct. (cm3) 100 1531 200 1941 300 2352 400 2762 500 3172 600 3583 700 3993 Your TV report should include the six steps in scientific inquiry and how they relate to the experiment in this assignment. © Pearson Education, Inc. All rights reserved. Lab 2—Making Sense of Density Ball Mass of Ball (g) Volume of Water (mL) Volume of Water and Ball (mL) Volume of Ball Density (g/mL) Au 312.114 228 244.2 16.2 19.27 Al 47.713 228 245.2 17.2 2.66 Analyze and Conclude 1. The gold sample had more mass than the aluminum sample because it was more dense. 2. Answers will vary depending on how much the students know about the different materials. The lead would be the most dense and the cork would be the least dense. You could determine this by measuring the mass and volume of each object. 3. Yes, since the density of aluminum is low, an airplane with the same amount of metal would be lighter. The density of an airplane is a factor in its ability to fly and the cost of fuel. Answer Key 151 sx07CAGr8_VPhyLab_Answer.fm Page 152 Friday, September 7, 2007 7:00 AM Lab 3—Investigation of Gas Pressure and Mass Mass (tons) External Pressure (psi) Internal Pressure from Meter (psi) Calculated Internal Pressure (psi) 0 14.7 14.7 0.5 14.7 51.2 51.3 2.5 14.7 197.3 197.8 Analyze and Conclude 6. They are very close. 1. 1000 lbs 7. 14.7 psi 183.1 psi 197.8 psi calculated 197.8 psi; the meter reads 197.3 psi. The numbers are within experimental error. 2. 7.5 cm 3. 27.3 in2 4. 36.6 psi 5. 14.7 psi 36.6 psi 51.3 psi, which is essentially the same as the pressure on the meter The internal pressure for the car tire is 32 psi 14.7 psi 46.7 psi. This is only one-fourth of the pressure calculated in 7. Lab 4—Pressure and Volume of a Gas 2. As the pressure is increased the volume decreases. Volume (cm3) 100 7436 200 3718 300 2478 400 1859 500 1487 600 1239 700 1062 152 Answer Key 1. The graph is a curve sloping down from the upper left. The line comes closer and closer to a volume of 1000 cm3 as the pressure approaches 700 kPa. The volume is largest when the pressure is the lowest. 2. The graph shows that as the pressure increases the volume decreases. 3. Nonlinear 4. If the pressure were decreased, the volume would increase because pressure and volume vary indirectly. © Pearson Education, Inc. All rights reserved. Pressure (kPa) Analyze and Conclude sx07CAGr8_VPhyLab_Answer.fm Page 153 Friday, September 7, 2007 7:00 AM Lab 5—Pressure and Temperature of a Gas 2. As the temperature is increased the pressure will increase. Temperature (°C) Pressure (kPa) Analyze and Conclude 1. The graph is a straight line sloping upward from the lower left to the upper right. 100 310.3 200 393.4 300 476.5 2. Yes, the graph shows that as the temperature increases, the pressure also increases. 400 559.7 3. linear 500 642.8 600 726.0 700 809.1 4. If the temperature were decreased, the pressure would also decrease because temperature and pressure vary directly. Lab 6—Changes Between a Solid and a Liquid © Pearson Education, Inc. All rights reserved. 1. Temperature is plotted on the vertical axis and time is plotted on the horizontal axis. The graph should show that when the water cools down the temperature of the water and ice mixture is approximately 0°C. For approximately 1.5 minutes the temperature does not change. After 1.5 minutes, the temperature increases gradually. The horizontal portion of the graph should be labeled ice/water mixture. The sloping line should be labeled liquid. 2. liquid and solid liquid The temperature remains constant at 0°C. This occurs when the ice is melting and becoming liquid water. Normally, the temperature increases as thermal energy increases because the molecules move faster, but during the change from solid to liquid the molecules are breaking free from each other and changing to a liquid and the temperature stays constant. The temperature begins to rise as soon as all of the ice is melted. The temperature rises because the thermal energy of the molecules is increasing causing them to move faster. Answer Key 153 sx07CAGr8_VPhyLab_Answer.fm Page 154 Friday, September 7, 2007 7:00 AM Lab 7—Changes Between a Liquid and a Gas Temperature at Boiling Pressure at Boiling 100.44°C 772 torr 1. The graph should be labeled Temperature (°C) on the vertical axis and Time (min) on the horizontal axis. The line rises steeply to the right from 25°C at zero minutes to about 100°C after about 1 minute. For the next three minutes, the line is horizontal. The portion of the line that is rising should be labeled water. The horizontal portion of the line should be labeled water and water vapor. 2. Temperatures may vary around 100°C. The temperature of the water increases as heat is added. The temperature increases because the water molecules are given more thermal energy. As a result they move faster and vibrate more. The temperature remains constant during the boiling process. This is because the heat that is being added to the water is being used to create water vapor instead of raising the temperature. Going Further 3. The boiling point is normally 100°C but could have been higher or lower in the virtual laboratory depending on the pressure. An increase in air pressure increases the boiling point. Lower air pressure decreases the boiling point. 4. The boiling point of water is directly related to air pressure. In the experiment the air pressure could have been higher, so the boiling point would have been too. If the air pressure was lower, the boiling point would have been too, but at the top of Mt. McKinley the air pressure would be much lower so the boiling point would also be much lower than 100°C. Lab 8—Thomson and Smaller Parts of Atoms 2. Electron gun 3. A spot in the center of the phosphor screen 4. The spot moves to the right. 154 Answer Key In the center of the phosphor screen 6. 34 mT of magnetic field balances 10 V of electric field and causes the spot to return to the center. © Pearson Education, Inc. All rights reserved. Negative; A phosphor screen 5. The spot moves to the left. sx07CAGr8_VPhyLab_Answer.fm Page 155 Friday, September 7, 2007 7:00 AM Lab 9—Rutherford and the Nucleus 2. Alpha particles 7. The hits show up every few seconds. 3. Gold 8. It takes nearly a minute for even a single hit to appear. 4. Phosphor screen 5. Spots of light Hits from alpha particles being deflected at small angles As the positively charged particles pass through the gold atoms they are attracted by the negatively charged electrons and their path is slightly bent. The alpha particles hit the screen at a rapid rate. 6. The hits are not quite as frequent and the forward scattering spot is no longer visible. 9. The alpha particles would have to be hitting a large mass in the center of the atom. The mass of the gold atom is not spread evenly throughout the atom. It is concentrated in a central atomic nucleus. 10. Mostly empty space 11. Most of the alpha particles came straight through the foil or were only slightly deflected. This evidence suggests that the atom is mostly empty space. But some alpha particles were deflected at large angles. These deflections could happen only if an alpha particle came close to or hit a large positive mass. Lab 10—Elements and the Periodic Table Symbol Color of Solution Atomic Number Atomic Mass Group Number Silver Ag colorless 47 107.87 11 Sodium Na colorless 11 22.99 1 Potassium K colorless 19 39.10 1 Cobalt Co pink 27 58.93 9 Copper Cu blue 29 63.55 11 Chromium Cr purple 24 52.00 6 Magnesium Mg colorless 12 24.31 2 Barium Ba colorless 56 137.33 2 Calcium Ca colorless 20 40.08 2 Vanadium V green 23 50.94 5 Nickel Ni green 28 58.69 10 Aluminum Al colorless 13 26.98 13 © Pearson Education, Inc. All rights reserved. Element Answer Key 155 sx07CAGr8_VPhyLab_Answer.fm Page 156 Friday, September 7, 2007 3:31 PM Analyze and Conclude 1. The number of protons and the number of electrons in an atom 2. 23 protons and 23 electrons 3. Because most elements consist of a mixture of isotopes with different atomic masses 4. Alkali metals: sodium and potassium Alkaline-earth metals: barium, magnesium, and calcium Transition metals: silver, cobalt, copper, chromium, vanadium, and nickel Mixed group metals: aluminum 5. Elements in the transition metal group are usually colored. Elements not in the transition metal group are colorless. Lab 11—Density of Solids and Liquids 5. Subtract the volume of the Virtual Fluid from the total volume of the Virtual Fluid and the plastic sample. Table 1 Sample Mass of Sample (g) Volume of Virtual Fluid (mL) Volume of Virtual Fluid and Sample (mL) Plastic 17.154 226.8 224 17.2 0.997 Volume of Sample (mL) Density (g/mL) 9. Subtract the mass of the empty beaker from the mass of the beaker and the alcohol. Table 2 Mass of Beaker and Sample (g) Mass of Sample (g) Volume of Sample (mL) Density (g/mL) Alcohol 101.310 279.168 177.858 225.8 0.788 Analyze and Conclude 1. To determine the volume of the solid, the solid must be completely covered by the liquid. If part of it was sticking out of the Virtual Fluid, the calculated solid volume would be less than the actual solid volume. The volume would be less by the amount of volume sticking out of the liquid. 2. Materials with a higher density than water sink. Materials with a lower density than water float. 156 Answer Key 3. The density of the plastic ball is 0.997 g/mL. The density of alcohol is 0.788 g/mL. Because the density of the plastic is higher than the density of the alcohol, the plastic would sink. 4. You would need to measure the mass and the volume of each sample and calculate the densities. A solid sample will float in any liquid that has a higher density and sink in any liquid that has a lower density. © Pearson Education, Inc. All rights reserved. Sample Mass of Empty Beaker (g) sx07CAGr8_VPhyLab_Answer.fm Page 157 Friday, September 7, 2007 7:00 AM Lab 12—Creating Chemical Compounds 8. black Test Tube Formula from Screen Color Before Color After Ratio 1 AgCl colorless white 1:1 2 PbCl2 colorless white 1:2 3 FeS yellow black 1:1 4 CuS blue black 1:1 5 PbS colorless black 1:1 6 Ag2S colorless black 2:1 Analyze and Conclude 2. No, both ions have positive charges. 1. 2– 3. SnCl4 Lab 13—Names and Formulas of Ionic Compounds Observation Table Ag+ silver Pb2+ lead Fe3+ iron Cu2+ copper Na2S (S2) sulfide black black black black NaCl (Cl) chloride white white NR NR Na2SO4 (SO42) sulfate NR white NR NR NaOH (OH) hydroxide pinkish NR red dark blue pink white red blue/white Ag+ silver Pb2+ lead Fe3+ iron Cu2+ copper Na2S (S2) sulfide Ag2S PbS Fe2S3 CuS NaCl (Cl) chloride AgCl PbCl2 NR NR Na2SO4 (SO42) sulfate NR PbSO4 NR NR NaOH (OH) hydroxide AgOH NR Fe(OH)3 Cu(OH)2 Ag2CO3 PbCO3 Fe2(CO3)3 CuCO3 © Pearson Education, Inc. All rights reserved. Na2CO3 (CO32) carbonate Analyze and Conclude Chemical Formula Table Na2CO3 (CO32) carbonate Answer Key 157 sx07CAGr8_VPhyLab_Answer.fm Page 158 Friday, September 7, 2007 7:00 AM Chemical Name Table Ag+ silver Pb2+ lead Fe3+ iron Cu2+ copper Na2S (S2) sulfide silver sulfide lead sulfide iron sulfide copper sulfide NaCl (Cl) chloride silver chloride lead chloride NR NR NR lead sulfate NR NR NaOH (OH) hydroxide silver hydroxide NR iron hydroxide copper hydroxide Na2CO3 (CO32) carbonate silver carbonate lead carbonate iron carbonate copper carbonate Na2SO4 (SO42) sulfate 2. Calcium sulfide, magnesium hydroxide, potassium hydroxide Analyze and Conclude 1. Ag2SO4, PbSO4, Fe2(SO4)3 Lab 14—Describing Chemical Reactions 3. The solution was clear. When NaOH was added, the solution turned a brown/pink color. Analyze and Conclude 6. The solution was clear but turned milky white as a solid precipitate formed. 1. Pb(NO3)2 Na2CO3 → 2NaNO3 PbCO3 2. Silver nitrate reacts with sodium sulfide to form sodium nitrate and silver sulfide. 3. 2AgNO3 Na2S → 2NaNO3 Ag2S 4. The solution is clear at the start but a solid black precipitate forms when Na2S is added. Mixture Initial Temperature T1 (°C) Final Temperature T2 (°C) NaCl(s) + H2O (l) 25.00 24.90 NaNO3(s) + H2O (l) 25.00 24.00 NaCH3COO(s) + H2O (l) 25.00 25.96 Analyze and Conclude 3. NaCl 1. NaCl: 0.10; NaNO3: 1.00; NaCH3COO: 0.96 4. heat NaNO3(s) → Na+(aq) NO3–(aq) NaCH3COO(s) → Na+(aq) 2. Endothermic: NaNO3; NaCl Exothermic: NaCH3COO CH3COO–(aq) heat 158 Answer Key © Pearson Education, Inc. All rights reserved. Lab 15—Using Energy to Observe Chemical Changes sx07CAGr8_VPhyLab_Answer.fm Page 159 Friday, September 7, 2007 7:00 AM Lab 16—Boiling Point Elevation 5. Amount of water, kind of solid dissolved. Table 1 Mass of NaCl 2.9399 g Boiling temperature of pure water 99.47°C Boiling temperature of solution 100°C Mass of NaCl 3.9994 g Change in boiling temperature +0.53°C Boiling temperature of pure water 99.47°C Boiling temperature of solution 100.21°C Change in boiling temperature +0.74°C Analyze and Conclude 1. The boiling temperature was higher. Mass of NaCl; Temperature Table 2 2. 100°C 99.47°C 0.53°C 3. To raise its boiling point, coolant is dissolved in the water that cools the engine. With the addition of the coolant, the water in the radiator remains a liquid over a larger temperature range. 4. The boiling point would increase. 9. When the mass of dissolved NaCl was increased, the amount of elevation of the boiling point increased. This is because the more ions of NaCl there are, the greater the interference with the normal evaporation and boiling of the water molecules. Lab 17—Endothermic vs Exothermic Data Table T1 T2 DT (T2-T1) Exothermic or Endothermic? NaCl (s) + H2O (l) 25 24.75 0.25 Slightly Endothermic NaNO3 (s) + H2O (l) 25 24 1 Endothermic NaCH3COO (s)+ H2O (l) 25 26 1 Exothermic NaOH (s) + H2O (l) 25 30 5 Exothermic © Pearson Education, Inc. All rights reserved. Mixture 10. Answers will vary. NaCl lowers the temperature of the solution, so it wouldn't freeze until the temperature was lower. 11. Answers will vary. Cold packs for injuries, chemical handwarmers, some glowsticks get warm after you snap them. Answer Key 159 sx07CAGr8_VPhyLab_Answer.fm Page 160 Friday, September 7, 2007 7:00 AM Lab 18—Acid-Base Reactions Analyze and Conclude 1. Yellow Blue 2. 25.00 cm3 of NaOH 3. The pH changed rapidly from low pH to high pH. All the acid was consumed, so the additional base caused the pH to change quickly. The indicator must change its color when the pH changes. 4. HCl(aq) NaOH(aq) ➔ H2O(l) NaCl(aq) 5. The presence of hydrogen ions (H+) The presence of hydroxide ions (OH–); They have combined to form water molecules; Hydrogen ions combine with hydroxide ions to form neutral water. 6. NaCl 7. The graph shows that the pH rises very slightly until 25.00 cm3 of base have been added. Then the curve rises sharply and quickly levels off near pH 12. 8. pH 7 Lab 19—Energy of a Chemical Reaction Analyze and Conclude 1. 25.00°C 28.3°C; 35 seconds 2. Approximately 3.375°C 4. If the temperature decreased, the reaction must be endothermic. The reaction would have drawn heat from the surrounding water and caused the water temperature to go down. 3. The reaction is exothermic because the temperature increased as heat was given off by the chemical reaction. Lab 20—Investigating the Properties of Alpha and Beta Particles 3. A spot in the center of the phosphor screen 4. The spot moves right. 5. The spot moves left. 7. Another spot 8. The spot moves to the left. It is opposite. Electrons move right when applying a 160 Answer Key magnetic field and alpha particles move left. 9. The spot moved to the right. Again, it is opposite. Electrons move left in the electric field and alpha particles move right.; The alpha particle is massive compared with the electron. It is more than 7000 times heavier! © Pearson Education, Inc. All rights reserved. 2. Electron Gun; Negative; Phosphor Screen sx07CAGr8_VPhyLab_Answer.fm Page 161 Friday, September 7, 2007 7:00 AM Lab 21—Measuring Speed Procedure 2. The ball that rolls across the table in a short time is going faster than the ball that takes a long time. The speed of the first ball is greater than the speed of the second. Table 1: Answers will vary. Analyze and Conclude 1. The graph shows a straight line starting from the point (0 s, 0 cm) and ending at the point corresponding to the time and distance at which the ball reached the end of the table. The line slopes upward from left to right. 2. All lines start from the point (0 s, 0 cm) and slope upward and to the right at different angles. Each line ends at the point corresponding to the time and distance at which that ball reached the end of the table. 3. The steeper the slope, the faster the ball moved. It would be even steeper than any of the lines on the graph. It would be less steep than any of the lines on the graph. 4. Table 2: Answers will vary. 5. Divide the distance between the two cities by the time it took to travel between them. Lab 22—Graphing Motion Analyze and Conclude 1. Graphs will vary depending on the masses used. © Pearson Education, Inc. All rights reserved. 2. Each point on the three lines shows the distance a ball traveled in the corresponding time. 3. They each have a different steepness (slope). The balls traveled at different speeds. Each reached the end of the table at different times. 4. The slopes tell the different speeds of the three balls. The ball with the least mass is the fastest and the most massive ball is the slowest. 5. The dog starts at position zero. In 4 seconds the dog travels 20 meters. The dog remains in one place for 4 seconds, and then travels 40 meters in 2 seconds. 6. The slope of the line from 0 seconds to 4 seconds is not as steep as the slope from 8 seconds to 10 seconds. That means that the dog must have moved more slowly at the beginning of the 10 seconds than at the end. Answer Key 161 sx07CAGr8_VPhyLab_Answer.fm Page 162 Friday, September 7, 2007 7:00 AM Lab 23—Acceleration 2. As the ball rises, it will slow down. As the ball falls, it will speed up. 4. The ball accelerates all along its path. As the ball rises, it slows down, so it experiences negative acceleration or deceleration. At the peak of the trajectory, the ball’s direction changes, so it is accelerating. As the ball falls it speeds up, so it is accelerating. Analyze and Conclude 4. A negative slope above the x-axis indicates the ball is slowing down. A negative slope below the x-axis indicates the ball is speeding up. 5. The plunger force affects how fast the ball is moving, but the acceleration is always the same either going up or coming down. The slope of the falling and rising is the same value. The acceleration is not affected by the force of the plunger. 1. Graphs will vary. 3. The velocity versus time graphs are not horizontal lines. They have slopes. The slope of a velocity versus time graph is a measure of the acceleration. Lab 24—Forces 3. The ball still fell even though the rocket was on, but it fell more slowly. 4. The object is to find the force that will make the net force zero. Then the forces are balanced. This occurs when the ball doesn’t go down or up. Table 1: Data will vary; Table 2: Data will vary. Analyze and Conclude 1. The forces in Table 2 were used in different directions. Sometimes the forces were balanced and sometimes they pushed the ball off at other angles. 2. The ball does not move. 3. The ball speeds up or changes direction. 4. The builders should understand that they need a net force stronger than the forces opposing the rocket’s motion. 2. 9.8 N A metal sled would be easier to push because metal has a smoother surface. It would not stick or grip the cement as much. Table: Results will vary. Analyze and Conclude 1. Friction between the sled and the table 2. Plastic on plastic was the best combination for sliding. Plastic is the smoothest of the available materials 162 Answer Key and produced the least friction. Rubber on rubber produced the most friction. The sled barely moved when the plunger hit the sled. 3. It would take more force to move the sled. 4. The larger the friction, the stronger the force must be to move the object. 5. Somewhere in between—the tire should be smooth so it can roll, but with enough stickiness to grip the road. © Pearson Education, Inc. All rights reserved. Lab 25—Measuring Friction sx07CAGr8_VPhyLab_Answer.fm Page 163 Friday, September 7, 2007 7:00 AM Lab 26—Acceleration and Friction Analyze and Conclude 3. The shape of the line is not as curved and is less steep. As the friction becomes greater, the sled cannot accelerate as well. 4. The shapes of the curves become less steep faster. 5. Friction causes the sled to slow down. The more friction there is, the faster the sled slows down. The rocket force causes the sled to speed up. Lab 27—Gravity and Free Fall Motion Analyze and Conclude 1. Individual graphs will vary. 2. Answers will vary. The graphs without air resistance are the same. The graphs with air resistance show that the small ball accelerates more slowly than the same ball without air resistance. The large ball with air resistance accelerates much more slowly and even stops accelerating. 3. Without air resistance, the balls are in free fall. Their mass and radius do not affect how fast they fall. Every object falls with the same constant acceleration when only the force of gravity is acting on it. 4. As the balls begin to fall, they have almost constant acceleration, just as if they were in free fall. But as the balls speed up, air resistance increases and they can’t accelerate as much. At some point, the force of air resistance becomes equal to the force of gravity and the ball stops accelerating. 5. When an object falls with air resistance, there will always be a time when the force of air resistance balances the force of gravity. This balancing point marks the end or termination of acceleration and the beginning of constant velocity for the remainder of the fall. 6. The balls would speed up much faster so the increasing air resistance would cause them to hit terminal velocity faster. © Pearson Education, Inc. All rights reserved. Lab 28—Newton’s First Law 1. Graphs will vary. Analyze and Conclude 2. The lightest mass was easiest. The most massive ball was hardest. The more mass an object has, the greater its inertia. 3. Because there is no friction, the rocket force is the only force working to change the motion or inertia of the ball. Any force will be enough to stop the ball eventually. 4. Any type of force could change the motion of the ball: friction, air resistance, or gravity. 5. The ball would keep moving at constant velocity forever. It doesn’t matter what the mass is. The greater the mass of an object, the greater its inertia is. Answer Key 163 sx07CAGr8_VPhyLab_Answer.fm Page 164 Friday, September 7, 2007 7:00 AM Lab 29—Newton’s Second Law The velocity versus time graphs show that the velocity is increasing linearly. The ball with the smallest mass and the greatest force had the greatest acceleration. 2. They will have some sort of slope. The velocity will be changing over time. Analyze and Conclude 1., 2. Graphs will vary. 3. The position versus time graphs are curved because as the ball travels farther, it moves faster. 4. Use a ball with a very small mass. 5. You can decrease the mass or increase the force, or both. Lab 30—Newton’s Third Law 2. Newton’s third law says that two colliding objects exert equal and opposite forces on each other. A force, exerted on a small mass, results in a large acceleration or velocity. The same force exerted on a large mass cannot accelerate it very much, so it moves slowly. 2. The heavy ball will hit the lighter ball just as hard as the light ball hits back. The light ball will bounce back going faster and the heavy ball will bounce back going slower. Analyze and Conclude 1. When the masses were the same, the velocities of each ball after the collision were the same. When one ball was more massive than the other, the light ball moved with large velocity and the heavy ball barely moved. 3. Answers will vary depending on the prediction. 4. Because the forces act on different objects Mass (kg) Velocity Before Velocity After Reaction Ball 1 10 –10 10 goes to the right Ball 2 10 10 –10 goes to the left Ball 1 20 –10 3.333 goes slower to the right Ball 2 10 10 –16.667 goes faster to the left Ball 1 50 –10 –9.216 goes slower to the left Ball 2 1 10 –29.216 goes faster to the left Ball 1 1 –10 29.216 goes faster to the right Ball 2 50 10 9.216 goes slower to the right Trial 2 Trial 3 Trial 4 164 Answer Key © Pearson Education, Inc. All rights reserved. Trial 1 sx07CAGr8_VPhyLab_Answer.fm Page 165 Friday, September 7, 2007 3:32 PM Lab 31—Conservation of Momentum Analyze and Conclude 1. Yes, because the total momentum before the collision equaled the total momentum after. 2. Yes, they would obey the law. Answers may vary for the second part of this question. 3. It could have a large velocity. 4. Answers will vary but should include the product of mass and velocity and the measure of motion. Trial 1 Mass (kg) Velocity Before (m/s) Velocity After (m/s) Momentum Before (mass x velocitybefore) Momentum After (mass x velocityafter) Ball 1 10 –10 10 –100 100 Ball 2 10 10 –10 100 –100 0 0 Total Momentum = Trial 2 Mass (kg) Velocity Before (m/s) Velocity After (m/s) Momentum Before (mass x velocity before) Momentum After (mass x velocity after) Ball 1 15 –10 –2 –150 –30 Ball 2 10 0 –12 0 –120 –150 –150 Total Momentum = Lab 32—Floating Objects © Pearson Education, Inc. All rights reserved. Table 1 (Sample Data) Table 2 (Sample Data) Volume Virtual Fluid (mL) 226.2 Mass of beaker only (g) 101.30 Mass of beaker and Virtual Fluid (g) 607.1 Volume of Virtual Fluid only (mL) 226.2 Volume of Virtual Fluid and steel (mL) 247.5 Mass of steel ball (g) 162.1 Analyze and Conclude 1. 505.8 g; Subtract the mass of the beaker from the mass of the beaker and the Virtual Fluid. 2. 2.24 g/mL 3. 247.5 mL 226.2 mL 21.3 mL m d V; The mass of the Virtual Fluid is m (2.24 g/mL)(21.3 mL) 47.7 g. 4. 47.7 g 0.477 kg; 0.477 kg 9.8 m/s2 0.467 N 5. The buoyant force acting on the steel ball is equal to the weight of the displaced fluid and is 0.467 N. 6. The force of gravity acting on the steel ball is its mass in kg multiplied by 9.8 m/s2 or 0.1621 kg 9.8 m/s2 1.59 N. 7. The force of gravity pulling down on the steel ball is much larger than the buoyant force pushing up on the steel ball, so the ball sinks. Answer Key 165 sx07CAGr8_VPhyLab_Answer.fm Page 166 Friday, September 7, 2007 3:37 PM Lab 33—Density and Buoyancy 5. Subtract the volume of the Virtual Fluid from the volume of both the Virtual Fluid and the plastic sample. Table 1 (Sample Data) Mass of Sample (g) Volume of Virtual Fluid (mL) Volume of Virtual Fluid and Sample (mL) Volume of Sample (mL) Density (g/mL) Plastic 18.355 228 246 18 1.02 Ice 17.071 229 248 19 0.898 Aluminum 46.698 227.5 245 17.5 2.67 Pine Wood 9.302 229 243.5 14.5 0.64 Sample 10. Subtract the mass of the empty beaker from the mass of the beaker and the ethanol. Table 2 (Sample Data) Mass of Empty Beaker (g) Mass of Beaker and Sample (g) Mass of Sample (g) Volume of Sample (mL) Density (g/mL) Ethanol 101.309 230.992 129.683 227 0.57 Water 101.309 327.856 226.547 226 1.00 Olive Oil 101.309 306.665 205.356 229 0.897 Mercury 101.309 3195.596 3094.287 227.5 13.60 Sample Analyze and Conclude 3. Density, not weight, determines whether or not an object will float or sink in a fluid. An object that is denser than the fluid it is in will sink. An object that is less dense than the fluid will float. 4. The density of the olive oil is 0.897 g/mL. Only the pine wood has a lower density (0.64 g/mL), so only the wood will float. 166 Answer Key 6. The density of olive oil is 0.90 g/mL. The density of water is 1.00 g/mL. Olive oil would float on water. 7. From top to bottom: ethanol, pine wood, olive oil, ice, water, plastic, aluminum, mercury. Density determines where the items are placed from lowest density on top to highest density on bottom. © Pearson Education, Inc. All rights reserved. 1., 2. See tables. 5. The density of mercury is 13.6 g/mL. None of the solids have a higher density and none will sink. sx07CAGr8_VPhyLab_Answer.fm Page 167 Friday, September 7, 2007 7:00 AM Lab 34—The Work of the Egyptians 3. Weight of sled = 490N 4. Minimum Pushing Force Time to reach top 491N 1min 26 sec 5. The length of the ramp must change. 6. Answers will vary. Data Table 1 Ramp Angle Ramp Length (m) Force (N) 90° 50 491 60° 57.74 425 45° 70.71 347 30° 100 246 10° 287.94 86 Ramp Angle Force (N) Ramp Length (m) Work (J) 90° 491 50 24550 60° 425 57.74 24539.5 45° 347 70.71 24536.37 30° 246 100 24600 10° 86 287.94 24762.84 7. Answers will vary. © Pearson Education, Inc. All rights reserved. Data Table 2 Answer Key 167 sx07CAGr8_VPhyLab_Answer.fm Page 168 Friday, September 7, 2007 7:00 AM Analyze and Conclude 8. The length of the ramp will have to increase if the angle decreases and you need to still reach the same height. 9. The steeper the angle, the greater the force required. 11. Since the Egyptians were limited in the amount of force they could get from manpower, it would be best to use the steepest ramp that would allow them to push the blocks up, so they wouldn’t have to push for very long. 10. The amount of work required was the same. It was not dependent on the length of the ramp. Lab 35—Falling Elevator 4. Answers will vary. Data Table 1 Mass (kg) Height (number of floors) Height (meters) Force (N) Time (s) 3000 20 80 30000 28 3000 20 80 40000 6 3000 20 80 29500 77 3000 20 80 35000 29 3000 20 80 42000 10 Answers will vary. It should take half as much force. 5. Answers will vary. Data Table 2 Height (number of floors) Force (N) Time (s) 1500 20 20000 6 1500 20 15000 28 1500 20 14800 51 1500 20 14750 77 1500 20 14700 80 168 Answer Key © Pearson Education, Inc. All rights reserved. Mass (kg) sx07CAGr8_VPhyLab_Answer.fm Page 169 Friday, September 7, 2007 7:00 AM 6. Answers will vary. WORK Force (N) Distance (m) Work (J) Full Elevator 29500 80 2360000 Half Full 14750 80 1180000 POWER Work (J) Time (s) Power (watts) Full Elevator 2360000 77 30649 Half Full 1180000 77 15324 Analyze and Conclude elevator. It doesn’t reduce the amount of force you have to pull with at all. It would be best to use a pulley system. 7. The elevator that was most full. It took more force to move it. 8. They reduce the amount of input force thus reducing the amount of work and power required. 10. For safety reasons, buildings are limited to the space and size of motor allotted to the elevators. This restricts the load an elevator can carry safely. 9. A single fixed pulley requires the same amount of input force as the output force, which is just the weight of the Lab 36—Thermal Energy 3. Answers will vary. © Pearson Education, Inc. All rights reserved. Data Table 1: Energy Level 1 Ball Number Mass (kg) Velocity (m/s) Kinetic Energy (J) 1 10 2.274 25.85538 2 20 2.372 56.26384 3 10 1.061 5.628605 4 15 3.036 69.12972 5 5 2.247 12.62252 6 1 1.5 1.125 7 100 1.7 144.5 8 200 2.062 425.1844 9 7 1.5 7.875 10 1000 1.965 1930.613 Total Kinetic Energy 2678.797 They will speed up, have more kinetic energy, which also means greater thermal energy. Answer Key 169 sx07CAGr8_VPhyLab_Answer.fm Page 170 Friday, September 7, 2007 7:00 AM 4. Answers will vary. Data Table 2: Energy Level 2 Ball Number Mass (kg) Velocity (m/s) Kinetic Energy (J) 1 10 10 500 2 20 5.049 25.92401 3 10 9.194 422.64818 4 15 3.949 116.9595075 5 5 20.34 1034.289 6 1 4.69 10.99805 7 100 1.708 145.8632 8 200 2.235 499.5225 9 7 8.589 258.1902235 10 1000 1.673 1399.4645 Total Kinetic Energy 4642.867171 5. Answers will vary. Table 3: Energy Level 3 Mass (kg) Velocity (m/s) Kinetic Energy (J) 1 10 6.531 213.269805 2 20 4.306 185.41636 3 10 8.817 388.697445 4 15 3.691 102.1761075 5 5 7.468 139.42756 6 1 9.177 42.1086645 7 100 4.236 897.1848 8 200 1.493 222.9049 9 7 12.759 569.7722835 10 1000 1.805 1629.0125 Total Kinetic Energy 170 Answer Key 4389.970426 © Pearson Education, Inc. All rights reserved. Ball Number sx07CAGr8_VPhyLab_Answer.fm Page 171 Friday, September 7, 2007 7:00 AM because it has the most amount of kinetic energy, which is what helps produce heat. Analyze and Conclude 8. The one with the greatest amount of energy, the last run. 11. It shows how molecules have smaller parts, which help to carry the energy of that system. This simply shows how the tiny atoms work inside a molecule. 9. As you add energy to the system, the kinetic energy increases. 10. The highest energy level would be the best to heat up another molecule Lab 37—Potential Energy to Kinetic Energy to friction or thermal energy. All of the mechanical energy in the beginning was stored in gravitational energy and since the velocity at the beginning was zero, the kinetic energy at the beginning was zero also. 3. Answers will vary. The sled has the same amount of energy everywhere on the ramp. 8. Because the ramp is frictionless, all gravitational potential energy is converted to kinetic energy and not lost Height of the Sled (Y) (m) Speed at the bottom (Vtot) (m/s) Initial Potential Energy (J) Final Kinetic Energy (J) 52.84 69296.29 69801.64 141.421 Data Table 2 © Pearson Education, Inc. All rights reserved. Initial: Height of the Sled (Y) (m) Speed (Vtot) (m/s) Potential Energy (J) Kinetic Energy (J) 141.421 0.00 69296.29 0 0.00 52.84 0.00 69801.64 Middle: Bottom: Data Table 3 Ramp Angle Height of the Sled (Y) (m) Speed at the bottom (Vtot) (m/s) Kinetic Energy (J) 45° 141.421 52.84 69801.64 60° 141.069 53.063 70392.05 15° 141.686 52.867 69872.99 Your choice: ___ Answer Key 171 sx07CAGr8_VPhyLab_Answer.fm Page 172 Friday, September 7, 2007 7:00 AM energy was conserved, when kinetic increased, potential decreased. Analyze and Conclude 14. The energy didn’t change. 16. Energy is lost to friction and thermal energy. 15. The kinetic energy increased as the sled sped up down the ramp. The total Lab 38—Temperature and Volume of a Gas 2. As the temperature is increased, the volume will increase. Analyze and Conclude 1. The graph is a straight line that slopes upward from the lower left to the upper right. Temperature (°C) Volume (cm3) 100 1531 200 1941 300 2352 2. Yes, the graph shows that as the temperature increases, the volume also increases. 400 2762 3. linear 500 3172 600 3583 700 3993 4. If the temperature were decreased, the volume would also decrease because volume and temperature vary directly. Lab 39—Specific Heat Data Table Al Au Stainless Steel 7.3547 51.0616 23.3374 volume of water (mL) 100 100 100 mass of water (g) 99.8 99.8 99.8 initial temperature of water (°C) 25.00 25.00 25.00 initial temperature of metal (°C) 200.00 200.00 200.00 max temp of water + metal (°C) 27.38 27.39 29.21 Specific Heat (J/g°C) 0.783 0.113 0.441 © Pearson Education, Inc. All rights reserved. mass of metal (g) Analyze and Conclude Answers will vary. DTwater 5 27.38°C 2 25°C 5 2.38°C Answers will vary. q = 99.8g 3 2.38°C 3 4.184 J/(°C?g) 5 993.8 J Answers will vary. DTaluminum 5 200°C 2 27.38°C 5 172.62°C Answers will vary. CAl = 993.8 J/(7.3547 g)(172.62°C) 5 0.783 J/°C?g Answers will vary. CAu = 997.98 J/(51.0616 g)(172.61°C) 5 0.113 J/°C?g Answers will vary. CSteel = 1757.94 J/(23.3374 g)( 170.79°C) 5 0.441 J/°C?g Answers will vary. The gold can will absorb the heat in the room faster and your drink will heat up faster than in the aluminum can. 16. Answers will vary. The steel would heat up faster than the aluminum, but that could lead to hot spots. Once the aluminum heated up, it would keep the heat longer than the steel pot would. 9. 10. 11. 12. 13. 14. 15. Answer Key 172 sx07CAGr8_VPhyLab_Answer.fm Page 173 Friday, September 7, 2007 7:00 AM Lab 40—Blackbody Radiation 3. Data Table Temperature (K) Wavelength (nm) 3000 950 3100 922 3200 880 3300 853 3400 839 3500 826 3600 798 4. The intensity increases as the temperature increases. The maximum shifts left as the temperature increases. 5. The peak intensity does not move far enough to occur in the visible region and is always in the infrared region. The fact that the peak intensity does not occur in the visible range does not mean that there is no visible light radiated. The curve shows significant intensity of light in the visible region, just not the peak intensity. 6. As the temperature increases, the peak height increases. You would think that we would get more and more light from light bulbs as they heat up. 7. Answers will vary. Repeated heating close to the melting point wears out the filament. Lab 41—Wave Properties of Light © Pearson Education, Inc. All rights reserved. 2. The laser because it provides light at a single wavelength. 500 nm 3.0 mm. 3. No. As the slit spacing increases, the number of lines in the diffraction pattern increases. 4. There won’t be an interference pattern if the spacing between the slits is smaller than the size of the wavelength. When the slits are farther apart, you will start to see more and more diffraction bands as the waves interfere more 5. Answers will vary. 6. Color changes from green to red. The number of lines also changes. 7. The pattern is the same after allowing enough photons to diffract. It cannot diffract. What you see as the diffraction pattern that builds up over time is really the statistics of where each individual photon will hit the screen. It is uncertain what each individual photon will do, but the properties of a large collection of photons can be easily predicted. 8. Light behaves like a particle, and the wave—nature of light is really a representation of the statistics or uncertainty exhibited in an experiment. Answer Key 173 sx07CAGr8_VPhyLab_Answer.fm Page 174 Friday, September 7, 2007 7:00 AM Lab 42—Particle Properties of Light 2. The laser emits coherent light, which is the same wavelength and in phase. 1 nW 400 nm Na, sodium metal foil The phosphor screen detects electrons, and it glows momentarily at the positions where the electrons impact the screen. The laser light is causing the ejection of electrons from the surface of the sodium metal. The signal is not as intense and flickers as each photon impacts the phosphor screen. 3. The signal is more intense than at 1 photon/second, but the same as at 1 nW. 4. The signal disappears. 450 nm. Wavelength (nm) Energy Light color 400 most Dark blue 600 least Orange 450 middle Light blue 6. Wavelength corresponds to the energy of light emitted but intensity is the amount of light. 7. Violet light has a shorter wavelength, but more energy than orange light. Violet light has enough energy to eject electrons but orange light does not. Lab 43—Atomic Emission Spectra 2. Orange 590nm 6. There are a lot more peaks in the Blue and Purple range. Data Table Color of Light (highest peaks in visible range) Sodium (Na) Yellow Mercury (Hg) Blue Neon (Ne) Red Hydrogen (H2) Blue-Green and Red Helium (He) Blue and Yellow 8. Answers will vary. Lab 44—Plane Mirror Images 3. Answers will vary. The object will look like it is farther and farther away. It will get smaller and smaller. 5. The image size did not change. 9. The image is flipped. The color order on the ball is reversed with every mirror. The object looks reversed. 174 Answer Key 10. The image seems as if it is located inside the mirror. 11. Answers will vary. © Pearson Education, Inc. All rights reserved. Gas sx07CAGr8_VPhyLab_Answer.fm Page 175 Friday, September 7, 2007 7:00 AM Lab 45—Concave Mirror Images 3. Answers will vary. The object will look like it is farther and farther away. It will get smaller and smaller. 7. The image be upside down and the Height Factor is greater than 1. The image is reversed. 4. The image is right side up and larger than the actual object. The image is flipped. 8. The image is still reversed; it is still upside down but smaller. The Height Factor can be less than 1. 6. It is ahead of the focal point. It is a virtual image. Height Factor: 2.278 9. The image disappears. You can’t see any image at all. Lab 46—Convex Mirror Images 3. Answers will vary. The image will get bigger. 6. The image looked bigger. It is still right side up. 7. The image gets bigger. It is still not as big as the original object. 8. The objects reflected in the convex mirror are smaller than we are used to seeing in plane mirrors, so we would think they would be farther away than they actually are. 9. Answers will vary. Lab 47—Looking at Images 3. Answers will vary. The image will change to a virtual image on the same side as the object. Data Table Distance of object from lens (cm) Distance of image from lens (in.) Inverted (yes/no) 26 12 yes smaller 0.375 20 14 yes smaller 0.625 16 16 yes same size 1.0 12 24 yes larger 2.0 6 24 no larger 4.0 Height Factor © Pearson Education, Inc. All rights reserved. 175 Answer Key Image bigger or smaller than object? sx07CAGr8_VPhyLab_Answer.fm Page 176 Friday, September 7, 2007 7:00 AM 5. No image. Analyze and Conclude 6. The focal point is where the image transitions between being real or virtual and switches which side of the lens it is on. 7. The image looks smaller and the image is inverted. 8. The image becomes virtual and not inverted. 9. You could take an object and move it until you find the place where it flips from inverted image to a virtual noninverted image. Lab 48—Ohm’s Law Data Table 1 Resistance Voltage (V) Current (A) 1 1.5 1.50 10 1.5 0.150 100 1.5 0.015 1000 1.5 0.001 10000 1.5 0.0 Data Table 2 Resistance Voltage (V) Current (A) 100 1.5 0.015 100 3 0.030 100 4.5 0.045 100 9 0.90 100 12 0.120 Analyze and Conclude 8. It means the current cannot flow as fast or as much. If increased too much then the current would not go at all. 9. The current increased proportionally. 10. The circuit is like a river because it has a current, which follows paths. The voltage source would be like water that flows over a waterfall, which makes the water flow fast and have a lot of 176 Answer Key 11. Yes it does. When you have a fraction if you increase the numerator then the number will get bigger, if you increase the denominator the number will get smaller. This is exactly what happened from our data as in answers 7 and 9. © Pearson Education, Inc. All rights reserved. 7. The current decreased proportionally. energy. The resistor would be like a dam, or something constricting the flow, and the current is like the water that flows through the obstacles and over the waterfalls. sx07CAGr8_VPhyLab_Answer.fm Page 177 Friday, September 7, 2007 7:00 AM Lab 49—Circuit Diagrams voltage source, or battery, to the other end. If something isn’t connected, then the current won’t flow. 4. Answers will vary. 5. Descriptions will vary. Analyze and Conclude 6. The circuit diagrams are neater and simpler, and it is easier to follow the current and see if everything is connected. 7. Current flows through the wires in a complete loop from one side of the 8. When you are building something electrical, and you need to see where the wires need to go. 9. Answers may vary. Some may include legos, rule books, game manuals, connect the dots. Lab 50—Building Electrical Circuits Data Table 1: Series Circuit Phases Lights? Brightness One Light Bulb Yes Bright Two Light Bulbs Yes Dimmer Three Light Bulbs Yes Even Dimmer Data Table 2: Parallel Circuit Resistor Number Lights? Brightness Two Light Bulbs Yes Bright Three Light Bulbs Yes Bright Analyze and Conclude © Pearson Education, Inc. All rights reserved. 5. The brightness was the same through all the light bulbs. The brightness decreased with more bulbs. 6. The brightness was the same through all the bulbs; the brightness wasn’t changed with more bulbs. 7. You would be able to design the circuit to achieve the appropriate outcome. If you need to be able to turn off one of the elements but have everything else work, you should use parallel. If you need everything to turn off when one thing is taken out, then use series. 8. I would plug them in and then break one of the bulbs, or take one out so the circuit is not complete see what happens to the rest. If some lights go out then I know that some are in series, if some stay on then I know that some are in parallel. 9. Some Christmas tree lights and fuses are in series. Home outlets are in parallel. 10. Answers will vary. The bulb in series gets brighter when there are more bulbs in parallel in front of it in the series. The bulbs in parallel have lower resistance, so the second bulb can burn brighter. Putting more bulbs in parallel drops the effective resistance even more, as if it were a tiny little light bulb, so that is why the second bulb can glow brighter. Answer Key 177 sx07CAGr8_VPhyLab_Answer.fm Page 178 Friday, September 7, 2007 7:00 AM Lab 51—Making Observations of Our Solar System orbit is also elliptical. The comet moves much faster when it is closer to Earth than when it is farther away. 4. The outside planets move more slowly than the inner planets. The orbits of the planets seem almost circular. Pluto’s orbit is elliptical or oval. The comet’s Time Display at the End of One Orbit (year:day) Period of One Orbit (in Earth years) Mercury 2006:88 0.24 Venus 2006:223 0.61 Earth 2007:0 1.00 Mars 2007:321 1.88 Jupiter 2017:319 11.87 Saturn 2035:157 29.43 Uranus 2089:362 83.99 Neptune 2170:286 164.78 Pluto 2253:338 247.93 Comet 2081:169 75.46 Object 5. Answers will vary. The orbits of the comet and the planets aren’t in the same plane (they are tilted with respect to each other), so there are only two points where they could intersect potentially, and it isn’t very probable that the comet and the planet would be exactly in that point of their orbit at the same time. 6. Answers will vary. See answer above for correct response. 7. Jupiter and Saturn have the most moons. Venus and Mercury don’t have any moons. 8. Answers will vary. Lab 52—Tracking the Phases of the Moon Analyze and Conclude 1. The light of the sun can illuminate only the side of the moon that faces it. As the moon orbits Earth, observers on Earth can see only the side of the Moon that faces Earth. That side may not be totally lit up. It depends on where the moon is in its orbit. 2. Answers will vary depending on the prediction. 178 Answer Key © Pearson Education, Inc. All rights reserved. 3. The light of the sun can illuminate only the side of the moon that faces it. As the moon orbits Earth, observers on Earth can see only the side of the moon that faces Earth. Depending on where the moon is in its orbit, the side of the moon that faces Earth may not be totally lit up. sx07CAGr8_VPhyLab_Answer.fm Page 179 Friday, September 7, 2007 7:00 AM Lab 53—Measuring the Orbital Speed of the Planets 2. Answers will vary. Analyze and Conclude 1. Answers in the table may vary. Earth’s acceleration is actually quite small, so you can’t feel it. 2. Yes, it is very fast. 3. Although Earth is moving very fast, a person cannot feel motion, just change in motion, or acceleration. The value of 4. The sun is pulling Earth toward it with such a strong gravitational force that the planet can’t escape even traveling at the calculated velocity. Lab 54—How Strong is Gravity? Analyze and Conclude 1. Graphs will vary. 2. The speed of falling is higher on some planets (Jupiter, Neptune) and lower on others (all other planets). Answers will vary depending on the planets chosen. 3. The speed is changing at a constant rate. This means that acceleration is constant and that there is a constant gravitational force. 4. Answers will vary. 5. Answers will vary. Lab 55—Why Pluto is Not a Planet Table 1: Observation Table © Pearson Education, Inc. All rights reserved. Planetary Object Mass (kg) Inclination Average Orbital (degrees) Radius (km) Object Radius (km) Mercury 3.3022 1023 7 5.65 107 2.44 103 Venus 4.8685 1024 3.39 1.08 108 6.05 103 Earth 5.9742 1024 0 1.50 108 6.37 103 Mars 6.4185 1023 1.85 2.26 108 3.40 103 Jupiter 1.8986 1027 1.3 7.80 108 7.15 104 Saturn 5.6846 1026 2.49 1.43 109 6.03 104 Uranus 8.6832 1025 0.77 2.86 109 2.56 104 Neptune 1.0243 1026 1.77 4.50 109 2.48 104 Pluto 1.314 1022 17.15 5.28 109 1.20 103 Answer Key 179 sx07CAGr8_VPhyLab_Answer.fm Page 180 Friday, September 7, 2007 7:00 AM Table 2: Orbital Radius Object Location 1 (km) Location 2 (km) Location 3 (km) Location 4 (km) Mercury 70155536 53805238 46259656 55687123 Venus 107938764 107208975 107926361 108653710 Earth 149650141 147182927 149828247 152178996 Mars 206612261 225794000 249225198 224193989 Jupiter 777383685 740765896 784393231 818390820 Saturn 1515085008 1428374172 1352415642 1431906595 Uranus 2733964553 2856727592 3002680357 2827555376 Neptune 4444438326 4495131842 4545769675 4498655572 Pluto 5160382426 4094273632 5079892983 6787210330 7. Object Radius Smallest -------- -------- -------- Medium Pluto Mercury Mars Venus Earth ------- -------- Uranus Neptune --------- Largest Saturn Jupiter --------- Largest Saturn Jupiter Mass Smallest -------- -------- -------- Medium Pluto Mercury Mars Venus Earth ------- -------- Uranus Neptune Inclination -------- -------- -------- Medium ------- -------- --------- Largest Earth Uranus Jupiter Neptune Mars Saturn Venus Mercury Pluto 8. Pluto has a much larger orbital radius. 9. Answers will vary. 10. The planets have moons that seem to orbit around the planet in the plane of the planets orbit; however, the moon of Charon orbits perpendicular to the orbital direction. The size of Charon is 180 Answer Key close to the size of Pluto, where many of the other planets’ moons are not close in size at all. 11. Answer will vary. © Pearson Education, Inc. All rights reserved. Smallest