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* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Which SACs in 2017? Some thoughts on choosing tasks for SACs. In the old course many teachers would have used the Extended Practical Investigation (EPI) to assess the Motion Area of Study and the Summary Report for Electric Power. Now the Practical Investigation is its own Area of Study in Unit 4, Electric Power has been split across two Areas of Study and the Summary Report has been renamed and re-designed as an 'Annotations of at least two practical activities ...' . There are also a number of new formats in which the assessment could be done, such as: report of a physics phenomenon design, build, test and evaluate a device explanation of the operation of a device proposed solution to a scientific or technological problem reflective learning journal or a critique of a blog in response to an issue. At least three different tasks must be chosen for Unit 3, so 2017 will mean new assessment tasks or at least new ways of doing them. There are several possible combinations of tasks. All the Areas of Study in Unit 3 have many possible practical activities, so the 'Annotation ...' task could be used for any Area of Study. The Fields Area of Study has three distinct components, Gravitational, Electric and Magnetic, so it may be difficult to design an assessment task, other than a conventional test that can assess across all three components. So an assessment task where the student focusses on one of the components, but that assesses aspects of a physics education that a test does not effectively assess measure, would be a useful complement for this Area of Study. Some of the new possibilities include: explanation of the operation of a device report on a physics phenomenon proposed solution to a scientific or technological problem reflective learning journal or blog in response to an issue The Electrical Energy Area of Study is very much about the technology of the generation and transmission of electrical energy. So the four possibilities for assessments tasks listed immediately above are very relevant here. Possible combinations of Assessment Tasks Motion Fields Electrical Energy Annotation of at least 2 Explanation of the operation of A critique of a blog on a practical activities from a a device technological or environmental logbook issue Data analysis of extension Annotation of at least 2 Explanation of the operation of material from three practical activities from a a device experiments. logbook Response to structured Report on a physics Annotation of at least 2 questions: Compare and phenomenon practical activities from a contrast Newton's and logbook Einstein's explanations of motion Suggestions for each of the tasks described above are detailed in the following pages. Prepared by Vicphysics Teachers' Network vicphysics.org VCE Physics: A SAC task for Unit 3 Outcome 1: Explanation of the operation of a device. Students work individually to research a device. The teacher can supply a list of devices, students may suggest others. As much as possible, each student should have a unique device to research. Some possibilities include: Electric fields electrostatic motor defibrillator Van de Graff paint spraying generator surface disinfection photocopier capacitor dust precipitator loudspeaker Magnetic fields Wien filter mass spectrometer electron microscope particle accelerators series wound DC Motor shunt wound DC motor fusion reactor magnetometers quadrapole magnet homopolar motor microphone three phase motor relays MRI Gravitational fields space elevator 3 stage rockets satellites at Lagrangian points Electrophorus ECG ion drive electric field sensor electroreceptors linac linear motor telephony analog meter industrial magnets AC synchronous motor electric eels credit card protection Kelvin water dropper Wimshurst machine magnetohydrodynamic drive Maglev trains rare earth magnets ammeter voltmeter eccentric orbits of GPS satellites gravitational slingshot The task is to answer two questions about the device: what does it do? and how does it work? Stage 1. In the first session in class, the students are advised of their device. Each student uses a log book to document their research, identifying precisely each source accessed and including the information gathered from that source and rating the value of the information as well as other comments by the student. This stage should be a minimum of one session, but no more than three sessions. At the end of this stage, the log book is handed in to the teacher, or in the case of an electronic log book, a print out is submitted. Stage 2. In another session the log books and print outs are handed back to the students. The students have 50 minutes to answer in writing the two questions above plus additional questions the teacher might like to include. The teacher may wish to give the students access to their text book. The log books can also be collected and contribute to the assessment. Discussion Questions: 1. How would you modify this task to suit your situation? 2. Can you suggest other devices? 3. Are there other ways of organising the activity? e.g. a) letting students choose their topic or does this raise authentication concerns? b) Could students work in pairs on the research part? c) Would you have enough class time to allow oral reporting? Is a mini-poster a possibility? d) Are there ways of using IT differently? 4. Which of the following additional resources would you like?: Table template for the student to record information from their research. Column headings might include: Title of source, access link, author, authority of author, key words, extract, rating, Do the questions on the test sheet need to be spelt out? Assessment criteria and descriptors Prepared by Vicphysics Teachers' Network vicphysics.org VCE Physics: A SAC task for Unit 3 Outcome 2: Explanation of the operation of a device One possible assessment task for Unit 3 Outcome 3 is the explanation of the operation of a device. Students work individually to research a device. The teacher can supply a list of devices, students may suggest others. As much as possible, each student should have a unique device to research. Some possibilities that relate to the electromagnetism include: Bicycle dynamo AC Generator Transmission line Transformer Inverter Three phase generator DC Generator Maglev trains Loudspeakers Magnetic damping Tesla coil Oudin coil The task is to answer two questions about the device: what does it do? and how does it work? Stage 1. In the first session in class, the students are advised of their device. Each student uses a log book to document their research, identifying each source accessed precisely and including the information gathered from that source and rating the value of the information as well as other comments by the student. This stage should be a minimum of one session, but no more than three sessions. At the end of this stage, the log book is handed in to the teacher, or in the case of an electronic log book, a print out is submitted. Stage 2. In another session the log books and print outs are handed back to the students. The students have 50 minutes to answer in writing the two questions above plus additional questions the teacher might like to include. The teacher may wish to give the students access to their text book. The log books can also be collected and contribute to the assessment. Discussion Questions: 1. How would you modify this task to suit your situation? 2. Can you suggest other devices? 3. Which of the following additional resources do you need?: Table template for the student to record information from their research. Column headings might include: Title of source, access link, author, authority of author, key words, extract, rating, etc Assessment criteria and descriptors Prepared by Vicphysics Teachers' Network, vicphysics.org VCE Physics: A SAC task for Unit 3 Outcome 1: Explanation of a physics phenomenon. Students work individually to research a phenomenon. The teacher can supply a list of phenomena, students may suggest others. As much as possible, each student should have a unique phenomenon to research. Some possibilities include: Electric fields Electroluminescence Photoconductivity Lightning Sprites Ball lightning St Elmo's fire Triboelectric series Triboluminescence Piezoelectric effect Plasma Seebeck Effect Peltier Effect Thermocouple Electrohydrodynamics Electric shock Whistlers Catatumbo lightning Dirty thunderstorms electroreception electric eels Magnetic fields Auroras Diamagnetism Paramagnetism Ferromagnetism Antiferromagnetism Ferrimagnetism Magnetoreception Rare Earth magnets Curie point Hysteresis Gravitational fields planetary motion gravitational slingshot The task is to answer two questions about the phenomenon: what does it do? and how does it work? Stage 1. In the first session in class, the students are advised of their phenomenon. Each student uses a log book to document their research, identifying precisely each source accessed and including the information gathered from that source and rating the value of the information as well as other comments by the student. This stage should be a minimum of one session, but no more than three sessions. At the end of this stage, the log book is handed in to the teacher, or in the case of an electronic log book, a print out is submitted. Stage 2. In another session the log books and print outs are handed back to the students. The students have 50 minutes to answer in writing the two questions above plus additional questions the teacher might like to include. The teacher may wish to give the students access to their text book. The log books can also be collected and contribute to the assessment. Discussion Questions: 5. How would you modify this task to suit your situation? 6. Can you suggest other phenomena? 7. Are there other ways of organising the activity? e.g. a) letting students choose their topic or does this raise authentication concerns? b) Could students work in pairs on the research part? c) Would you have enough class time to allow oral reporting? Is a mini-poster a possibility? d) Are there ways of using IT differently? 8. Which of the following additional resources would you like?: Table template for the student to record information from their research. Column headings might include: Title of source, access link, author, authority of author, key words, extract, rating, etc Do the questions on the test sheet need to be spelt out? Assessment criteria and descriptors Prepared by Vicphysics Teachers' Network, vicphysics.org Data Analysis of extension material from three Motion experiments. A number of the experiments in the Motion Area of Study provide an opportunity to be extended. These are: Centripetal Acceleration Experiment Usually in this experiment students investigate the relationship between the number of washers on the end of the fishing line and the frequency of the revolving rubber stopper. The mass of the stopper and the radius are kept constant. In the data analysis task students are supplied with a table of data. The table contains the maximum, minimum and average values for frequency squared for several values for the number of washers for three different radius values as in the following example. No of washers Min Radius = Radius = Radius = Freq2 Max Freq2 Max Freq2 Max Ave Min Ave Min Ave The student's task is determine the relationship between the radius and the number of washers for a fixed frequency by the following steps: Graph the number of washers against Frequency squared for each radius, including error bars using the max and min data. The graph should have three lines passing through the origin, each with a different gradient. To find how the number of washers depends on the radius for a fixed frequency, rather than do the experiment, which would be physically impossible, the above graph can be used by drawing a vertical line through the three graphs at a chosen value for the frequency squared. Then at the points where this vertical line crosses each of the three graphs, the student reads off a pair of values for the radius and the number of washers. These three pair of values can then be graphed with the number of washers against radius and their relationship determined. Describe the relationship between the radius and the number of washers acknowledging the uncertainty in the data. Potential Energy in a Spring In this experiment a student measures the extension of a spring with increasing number of slotted masses to produce a Force versus extension graph and determines the spring constant. In the second part of the experiment they attach a known mass to the spring, lift the mass up so that the extension is zero and then release the mass. They measure the maximum extension, that is the extension when the falling mass stops. With this data the student is able to graph on the one set of axes the following graphs of energy versus distance with distance measured downwards from zero extension,: Spring potential energy versus extension Gravitational potential energy versus distance fallen Total potential energy versus distance from zero extension (the sum of the other two graphs) Total energy versus distance (A straight line from the total potential energy at zero extension to the total potential energy at maximum extension. This should be close to a straight line, allowing for small friction losses, etc) Prepared by Vicphysics Teachers' Network, vicphysics.org E Ext The additional tasks are: What does the gap between the total energy graph and the total potential energy graph represent? Measure the size of this gap off the graph for several distance values from zero extension to maximum extension and graph them along the bottom of the axes. Determine the extension value with the maximum value of the gap From the Force versus Extension graph of the spring determine the extension for the mass used in the drop and compare this answer with the answer to the previous question. Explain the motion of the dropped mass from the point of view of the forces acting on it and also from an energy point of view. Make reference to extension value determined in the previous two questions. Momentum and Kinetic Energy is a collision Two air track gliders, one heavy and one light, approach at speed. They collide. The lighter glider rebounds, the heavier glider follows. Mass Heavy glider Speed direction Speed before after direction Mass Speed before Light glider direction Speed after direction Using the gliders' mass values and their velocities before and after collision, calculate the total momentum before and after collision and the total kinetic energy before and after. Discussion Questions: Is this an appropriate task for data analysis? Are there other experiments that could be used? Would you allow students to use their logbooks, textbooks? Prepared by Vicphysics Teachers' Network, vicphysics.org A critique of a blog on a technological or environmental issue Internet media articles are often accompanied by an extensive exchange of comments. Many of these are on technological and environmental issues that have a basis in physics. Such issues include: Transmission of electric power Safety of electromagnetic devices Electric cars Maglev trains Major science projects such as the space research, LHC, Synchrotron, etc Common source of quality articles are: The Conversation Students can apply their physics understanding to the analysis of original article and the subsequent discussion. Some questions to guide analysis of an article and the discussion that follows: Article: 1. What is the main point of the article? 2. What are the subsidiary points in the article? 3. Are the scientific ideas correctly used? 4. What evidence does the author cite? 5. Does the evidence come from reputable sources? 6. Are the arguments presented legitimate and relevant? Author: 1. Who is the author and are they qualified to write about this topic? 2. Does the disclosure statement about their funding sources raise a question mark about the article? Comments: 1. Summarise the general positions about the article that are expressed in the comments. 2. Do the comments use scientific ideas correctly? 3. Do the comments cite other reputable evidence? 4. Are the arguments in the comments legitimate and relevant? 5. What proportion of the comments make a cogent contribution to the discussion? 6. Does the author of the article participate in the discussion. Conclusion: 1. What is your view? Discussion questions: 1. Is there enough physics in this activity to use it as an assessment task? 2. Could several articles be used with the class or should the whole class use the same article? 3. What are some good sources of articles? 4. What additional resources would be useful? Prepared by Vicphysics Teachers' Network, vicphysics.org Additional resources Key words search: Wind Energy Renewable energy Nuclear power Magnetic field Space weather Electromagnetic field Articles in The Conversation Nuclear power deserves a level playing field (43 comments) Ball lightning exists … but what on Earth is it? (10) Heavens above! What made the cosmic flash that lit Earth today? (14) Let there be light! Celebrating the theory of electromagnetism (51) Earth’s magnetic heartbeat, a thinner past and new alien worlds (11) Magnetic fields can control heat and sound (13) Can you be allergic to your Wi-Fi? (218) Scaremongering on Today Tonight: the truth about wireless radiation risks (18) No, we’re not all being pickled in deadly radiation from smartphones and wifi (74) Do mobiles give you brain cancer? The verdict’s still on hold (17) Do Wi-Fi and mobile phones really cause cancer? Experts respond (330) Can magnetically levitating trains run at 3,000km/h? (10) Magma power: how superheated molten rock could provide renewable energy (11) How to help energy demand match renewable supply (8) Catching the waves: it’s time for Australia to embrace ocean renewable energy (173) Kangaroo Island’s choice: a new cable to the mainland, or renewable power (44) Britain is only just beginning to exploit its vast resources of offshore wind (51) The next solar revolution could replace fossil fuels in mining (50) Explainer: what is solar thermal electricity? (10) Set the controls for the heart of the sun: time for solar courage (118) Wind and solar PV have won the race – it’s too late for other clean energy technologies (130) Pumped hydro energy storage – making better use of wind (63) How pushing water uphill can solve our renewable energy issues (241) Deaths at Dreamworld theme park could lead to safety changes for amusement rides (16) How to build a starship – and why we should start thinking about it now (13) Space debris: what can we do with unwanted satellites? (8) Explainer: how do satellites orbit the Earth? (13) Companions of Earth: minimoons, quasi-satellites and horseshoes (11) The Australian’s campaign against wind farms continues but the research doesn’t stack up (62) Is life on Earth due to a quirk in the laws of physics? (59) Prepared by Vicphysics Teachers' Network, vicphysics.org VCE Physics: A SAC task for Unit 3 Outcome 3 Annotations of at least two practical activities from a practical logbook _____________________________________________________________________________________ Outcome 3 On completion of this unit the student should be able to investigate motion and related energy transformations experimentally, analyse motion using Newton’s laws of motion in one and two dimensions, and explain the motion of objects moving at very large speeds using Einstein’s theory of special relativity. To achieve this outcome the student will draw on key knowledge outlined in Area of Study 3 and the related key science skills on pages 11 and 12 of the study design. _____________________________________________________________________________________ Questions and considerations in running the pre-SAC experiments and the “in-class” SAC The following are some things for the teacher to consider for this type of SAC, and also possible suggestions (where relevant or applicable) have been made for the teacher’s consideration: Questions: Practical activities range from demonstrations, POE's, round robins of task, self-paced exercises, formal experiments to extended investigations. Should this assessment task for the Motion Area of Study focus on experiments? That form has been adopted for this document. What does 'annotation' mean? Is it commentary and answers to questions as the experiment is being conducted or is it done some time later? How many experiments should be the focus of this SAC? How should this SAC be implemented? (e.g. teacher provides a series of questions in relation to the experiments completed, with student responses forming the basis of the “annotations” required for this SAC) Is it acceptable to bring in some of the Key Knowledge bullet points from the Special Relativity part of this Outcome? Considerations - teacher could consider providing students with the objective(s), all materials/resources needed, and the procedures to be used for each experiment; this will ensure “base consistency” in how an experiment will be run, while also providing opportunities for students to offer suggestions to improve the experimental setup, as well as responding to questions that form the basis of this “annotations” SAC) - students can work independently and collaboratively during the course of the experiment, but the SAC is completed individually - teacher could allow students to choose the format for displaying their results rather than providing them with a table and headings, in order to allow the students to demonstrate their ability to record and display results using appropriate conventions (including units of measure) - by referring students to the procedure and results of their experiment in the SAC will give them a context for demonstrating an understanding of errors associated with each experiment, rather than simply recalling the key ideas relating to errors Prepared by Vicphysics Teachers' Network, vicphysics.org At Least Two Experiments Some possible experiments and questions which could form the basis of the annotations for this SAC are shown in the table below. Many other suitable experiments can be undertaken by teachers. An appendix at the bottom of this document provides some additional information. Experiments Questions that form a part of the Assessment? Investigating Newton’s 2nd Law on an Inclined Plane - students will demonstrate their understanding of forces in one and two dimensions - optionally students can explore the concept of work done as the cart moves up the incline Draw all the forces acting on the dynamics cart and the mass. What happened to the magnitude of the acceleration of the cart as the slope of the incline increased and everything else remained unchanged? Explain your answer with calculations. What happened to the magnitude of the acceleration of the cart if the hanging mass increased and everything else remained unchanged? Explain your answer with calculations. Identify two specific sources of equipment error that may have contributed to large percent differences between the theoretical and experimental methods for determining the acceleration of the system. Identify two specific sources of human error that may have occurred in this experiment. How would you modify this experiment to determine the effect that increasing the mass of the cart has on the motion given to it by a constant force? Projectile Motion (horizontal projection) - students investigate motion in two dimensions (including developing an understanding of the motion of a projectile in Earth’s gravitational field) - students will gain experience in determining the range of a projectile for different horizontal velocities - students will gain experience in calculating the initial horizontal for a given range and vertical displacement Write a definition for the term ‘projectile’. Discuss two methods for determining the horizontal velocity of the object in this investigation. How does the range compare to the horizontal velocity? Include a reference to your hypothesis (e.g. how did the relationship between range and velocity compare with your hypothesis?) What is the most important type of error in this experiment? Give an example that applies to this experiment. How would the launch velocity be different if the mass of the projectile was greater than that of the projectile used in the experiment? What about if the mass was less than the object mass used in this experiment? Explain, using a calculation what would happen to the range of an object, and its time of flight, if the projectile was launched with the same initial launch speed, but at an angle of 30º to the horizontal. Prepared by Vicphysics Teachers' Network, vicphysics.org Investigating Horizontal Circular Motion - students will be investigating the relationship between centripetal force acting on an object moving in a circle of fixed radius and the period of its motion - students will extend their understanding to solving circular motion problems on a larger scale Identify two physical quantities in this experiment that you attempted to maintain constant for each of your trials. Explain what is meant by the period of an object when it is undergoing circular motion. Provide an example calculation as part of your response to this question (e.g. a calculation to the problem “If an object revolves 50 times in 20 seconds, what is the period of the object?”). Identify the formula that determines the magnitude of the centripetal acceleration from the data that you are able to measure in this experiment (e.g. students should be able to measure radius ‘r’ of string and determine the tangential speed ‘v’). Sketch a graph of centripetal force as a function of the reciprocal velocity squared (i.e. graph of Fc vs 1/v2). Discuss the error that is introduced if the string is not moving in a horizontal plane (i.e. the stopper is allowed to sag). You should include specific reference to the stopper’s weight and its effect on the tension on the string. If the mass of the stopper were increased, describe what would happen to the force needed to keep the stopper in “orbit” if the tangential speed and radius remained the same? How would the orbital period change? Use calculations to support your answer. If the radius of the string was increased while maintaining a constant mass and tangential speed, how would the centripetal force change to compensate? Use calculations to support your answer. Based upon your understanding of acceleration in a horizontal plane, how would you expect that doubling the speed of the object to affect the centripetal force? The concepts examined in this practical task can be extended to satellite motion. Identify the cause of the centripetal force of a communications satellite which is in geosynchronous orbit about Earth. Note: question(s) requiring students to undertake calculations involving satellite motion could be potentially added. Prepared by Vicphysics Teachers' Network, vicphysics.org Energy Transformations (converting PE to KE) - using an inclined plane, students will roll a dynamics cart down the incline in order to investigate how the sum of the cart’s kinetic energy and the work done against friction compare with the cart’s loss of potential energy Explain the energy transformations that take place as the cart rolls down the incline (responses need to refer to the Law of Conservation of Energy?) Describe an experiment that you could perform to determine if the mass of the cart has any effect on the amount of energy required to overcome friction. If the cart was replaced by a block of wood on the inclined plane, how would you expect the values for kinetic energy and work done against friction to change? What happens to the energy spent in overcoming friction? Conservation of Momentum - students will gain an understanding of momentum and the principle of conservation If both carts have the same mass, describe the velocity of each cart. When the connection between the two carts is ‘broken’, how do the forces exerted on each cart by each cart’s spring compare? How does the speed of the cart with greater mass compare to the cat with less mass? Explain what would happen to the momentum of the two carts if the springs were stiffer. Identify the two most likely sources of friction that could produce errors in this experiment. Discuss the consequences of the table (used to support your experimental setup) not being perfectly level. This experiment can be used to simulate a rifle firing a bullet. In the case of a rifle and the bullet, the bullet attains a high speed, but the rifle does not. Explain the reason for this. In the movie Eraser, an aluminium bullet is fired at near light speed. If the rest mass of the bullet is 250gram, then calculate the relativistic mass if the aluminium round was travelling at 0.8c. Changes in Potential Energy? students measure and graph the extension of a spring against force students drop of a mass from zero extension and measure the maximum extension. students use the Force vs extension graph and the dropped distance to generate energy versus distance graph for elastic potential energy, gravitational potential energy, then determine graphs for total energy and kinetic energy. Describe the force extension graph Use the graph to determine the spring constant Describe two ways to determine the spring potential energy stored in the spring Not all of the gravitational potential energy of the mass before it is dropped is transferred to spring potential energy at the bottom of the fall. Suggest where the missing energy may have gone. The graph of kinetic energy against distance can be used to determine the extension where the speed is greatest. Knowing the forces acting on the falling mass explain where you expect this point to be. Prepared by Vicphysics Teachers' Network, vicphysics.org Appendix The level of equipment and other materials will vary between schools. In theory, all of these practical activities can be run with basic equipment, or equipment which can be easily made, ideally by the students. Further information in this regards can be provided. Investigating Newton’s 2nd Law Possible Equipment/Materials - Dynamics cart - Pulley and string - Pulley clamp - Weights (various) - Ruler - Ticker timer, photogate, video analysis, Arduino microcontroller (or similar sort of data collection or recording equipment) Horizontal Projection Possible Equipment/Materials - large marble or steel ball bearing - tape measure or metre ruler - stop watch (or video analysis software & hardware) - carbon paper (or similar) to measure landing point of object Investigation Horizontal Circular Motion Possible Equipment/Materials - Balance (for measuring mass) - Glass tubing (or similar) - Masking tape or alligator clip (to fix the radius of rotation of the string) - Metal washers - Rubber stopper (or similar such mass) - Stopwatch - String (approx. 1 metre) - Paper clip to support washers Image credit: Taffel, Baumel & Landecker, 1966 Prepared by Vicphysics Teachers' Network, vicphysics.org Energy Transformations (converting PE to KE) g Conservation of Momentum Possible Equipment/Materials - two carts - spring system to provide simulated “explosion” - ticker timer, video analysis, Arduino microcontroller (or similar sort of data collection or recording equipment) http://cgscomwww.catlin.edu/sauerb/Ph12/PH12_Labs/PH12_Lab_17_Explosion_files/image002.jpg Prepared by Vicphysics Teachers' Network, vicphysics.org