Download Essential Physics Activities on a Budget Price

Essential Physics Activities on a Budget Price
Low Cost Physics
Activities
Center for Mathematics and Science
Education
Texas A&M University - College Station
(Note: This web page was constructed using Microsoft FrontPage 2002 and is best viewed
using Internet Explorer)
Physics experiments/activities do not have to be costly in time or resources. Teachers
also do not need to limit their equipment purchases to "high tech" or specialty materials
sold exclusively through science supply catalogs. Many valuable data collection activities
can be performed using inexpensive materials that may be purchased from local
department, hardware, and/or toy stores. The activities contained in the chart below
represent a few of what I personally consider the "best for the buck" when it comes to
introductory physics' essential laboratory activities on a tight budget. I have used all of
them in high school and/or introductory undergraduate physics courses.
Activities similar to these using a variety of materials may be found in numerous lab
resource materials. The purpose of this web page is not to introduce new and/or unique
lab activities, but to present some of the most common and valuable lab experiences
involving real data collection in a format for use with inexpensive materials. Activity
worksheet documents are presented in both PDF and Microsoft Word format so that they
may be easily downloaded, printed, and/or modified according to the individual needs of
each user.
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Essential Physics Activities on a Budget Price
Click on a MS Word or PDF "Worksheet Link" to download an
experiment/activity worksheet. Click on the "To the Teacher" link to view
suggestions and information regarding the activity, materials, and
approximate costs. "Other Links" provides links to other web pages with
activities/information/simulations related to the chosen physics topic (all links
active as of 3/9/2004).
Activity
Worksheet
Link
To the
Teacher
Other Links
1
Precision of Lab
Equipment
MS Word, PDF
link
link1 link2
link3
2
Constant and Relative
Velocity
MS Word, PDF
link
link1 link2
link3
3
Motion Graphs (Virtual
Activity)
MS Word, PDF
link
link1 link2
link3
4
Accelerated Motion
MS Word, PDF
link
link1 link2
link3
5
Free Fall (Virtual Activity)
MS Word, PDF
link
link1 link2
link3
6
Resultant Vectors
MS Word, PDF
link
link1 link2
link3
7
Softball Throw
MS Word, PDF
link
link1 link2
link3
8
Newton's 2nd Law (Virtual
Activity 1)
MS Word, PDF
link
link1 link2
link3
9
Newton's 2nd Law (Virtual
Activity 2)
MS Word, PDF
link
link1 link2
link3
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Essential Physics Activities on a Budget Price
10
The Pendulum
MS Word, PDF
link
link1 link2
link3
11
Sliding Friction
MS Word, PDF
link
link1 link2
link3
12
Forces in Equilibrium
MS Word, PDF
link
link1 link2 link3
13
Work and the Inclined
Plane
MS Word, PDF
link
link1 link2
link3
14
One-Dimensional
Collisions (Virtual Activity)
MS Word, PDF
link
link1, link2,
link3
15
Two-Dimensional
Collisions (Virtual Activity)
MS Word, PDF
link
link1, link2,
link3
16
Torque and Rotational
Equilibrium
MS Word, PDF
link
link1 link2
link3
link
link1 link2
link3
17
Power
MS Word, PDF
18
Wave Modeling
MS Word, PDF
link
link1 link2
link3
19
"Slinky" Waves
MS Word, PDF
link
link1 link2 link3
20
Ripple Tank (Virtual
Activity)
MS Word, PDF
link
link1 link2
link3
21
Resonance: Speed of
Sound
MS Word, PDF
link
link1 link2
link3
MS Word, PDF
link
link1 link2
link3
PowerPoint Slide
link
link1 link2
link3
22
23
Palm Pipes and Chimes
Reflection in Plane
Mirrors
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Essential Physics Activities on a Budget Price
24
Full Length Mirrors
MS Word, PDF
link
link1 link2
link3
25
Curved Mirror Diagrams
MS Word, PDF
link
link1 link2
link3
26
Index of Refraction
MS Word, PDF
link
link1 link2
link3
27
Lens Diagrams
MS Word, PDF
link
link1 link2
link3
MS Word, PDF
link
link1 link2
link3
MS Word, PDF
link
link1, link2,
link3
MS Word, PDF
link
link1 link2
link3
28
29
30
Images in Converging
Lenses
Color
Electrical Circuits and
Conductivity
31
Ohm's Law
MS Word, PDF
link
link1 link2
link3
32
Light Bulb Circuits
MS Word, PDF
link
link1 link2
link3
33
Electrical Energy Costs
MS Word, PDF
link
link1, link2,
link3
34
Electromagnets
MS Word, PDF
link
link1 link2
link3
35
Electric Motors
MS Word, PDF
link
link1 link2
link3
MS Word, PDF
link
link1 link2
link3
36
Simulated Radioactive
Decay
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Essential Physics Activities on a Budget Price
Recently developed video analysis technology offers an exciting and relatively
inexpensive way to analyze many types of one and two-dimensional motion. Go to
http://www.science.tamu.edu/CMSE/videoanalysis/index.htm to learn more about
some of the currently available video analysis programs, including one free program
that may be downloaded from an internet site linked to the page. Also linked to this
site are 19 video clips of many types of motion commonly studied in introductory
physics and physical science courses and suggestions for their use. The 36 activities
linked to this page and the 19 video analysis activities provide an excellent way for an
entire introductory level physics class to include 55 laboratory activities at an
unbelievably low cost.
In addition to these activities and web site links, physics teachers of all levels may be
interested in the following web sites offering tutorials, downloadable software, etc... :
Name
Description
URL
Link
Graph Paper
Create numerous types of custom graph paper
Printer Program
link
The Diagnoser
Project
A web-based assessment program that serves as a
formative diagnostic of student content knowledge
link
MERLOT
A search engine for science web sites
link
NetLogo
A modeling program useful for many science areas
link
Journal of
Online journal directly related to issues in physics
Physics Teacher
teaching and the preparation of physics teachers
Education Online
link
Singing Science
"Cheesy" science songs from the 1950s and 1960s
Records
link
Physics 2000
Very comprehensive tutorial program
link
The Physics
Classroom
Very comprehensive tutorial program
link
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Essential Physics Activities on a Budget Price
Conceptual
Physics SURF
Informative site supplementing Paul Hewitt's Conceptual
Physics textbook
link
For more information or comments about this web page or its activities,
to suggest other activities, or to request a workshop or professional
development session demonstrating the use of the activities, please contact:
Joel A. Bryan, Ph.D.
[email protected] (979) 458-0604
Center for Mathematics and Science Education
Texas A&M University - Mail Stop 4232
College Station, TX 77843-4232
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CMSE Phys
Precision of Lab Measurements
Triple Beam Balance
Record the mass, in grams, of three (3) common objects using the triple beam balance.
Object
Mass, g
When using this triple beam balance to find mass, you should record your values to the nearest
______________ of a gram because __________________________________________
_______________________________________________________________________.
Spring Scale
Record the weight, in Newtons, of three (3) common objects using the spring scale.
Object
Weight, N
When using this spring scale to find weight, you should record your values to the nearest
_________________ of a Newton because _____________________________________
_______________________________________________________________________.
Meter Stick
Record the length of three (3) common objects using the meter stick.
Object
Length, cm
When using this meter stick to measure length, you should record your values to the nearest
_____________ of a centimeter because _________________________
_______________________________________________________________.
Write a letter to a person of your choice in which you explain the rules for recording
volume values using as examples 3 beakers that are graduated in ones, in tens, and in
hundreds of milliliters (mL). Include a sketch of each type beaker in your letter.
CMSE Phys
Constant Velocity (Speed)
Objective: Measure distance and time during constant velocity (speed) movement.
Calculate average velocity (speed) as the slope of a “Position vs. Time” graph.
Equipment: battery operated vehicles, stopwatch, meter stick or measuring tape
Procedure:
1. Complete the table by timing each vehicle as it travels the indicated distance.
2. Perform two time trials for each distance and take the average value as your accepted time.
3. Use the distances traveled and average time s to make a “Distance vs. Time” graph (always named as
“y vs. x”) using MS Excel. Label this and all graphs as directed in class.
4. Use the MS Excel “Add Trendline” function to draw the best straight lines through your data
points and to compute the “best fit” equations for the lines.
5. Record the equation for each line on the graph. The slope of each line, given with the units
associated with the y- and x-axes, is the average velocity (speed) of each vehicle. Use this
information to write the speed of each vehicle on the graphs next to each line.
6. Print your graph or graphs.
Distance,
meters
0
0.5
1.0
1.5
2.0
2.5
3.0
1
0
Vehicle I
Vehicle II
Time Trials, seconds
Time Trials, seconds
2
0
AVG.
0
1
0
2
0
AVG.
0
Questions:
1.
Did each vehicle appear to maintain a constant velocity (speed)? _____
How can you tell by looking at a “position vs. time” graph if the velocity (speed) is constant?
2. How should the “position vs. time” graph of a faster car compare with the graph of a slower car?
1
CMSE Phys
Relative Velocity (Speed)
In this portion of the lab, you will determine the relative velocity (speed) of your two vehicles as they
1) approach each other from opposite directions, and 2) as the faster vehicle approaches and catches
up to the slower one from behind.
1)
Based on the average speeds of the two vehicles that you determined in Part I, what do you expect
the relative speed of the vehicles to be as they approach each other from opposite directions?
(i.e., At what rate should they close in on each other?) _______
Why?
2) What do you expect the relative speed to be as the faster vehicle catches up to the other one
from behind? (i.e., At what rate does the faster one close in on the other?) _______
Why?
Relative Velocity (Speed) Approaching from Opposite Directions
Procedure:
1. Place the vehicles facing each other the distance apart indicated in the table.
2. Turn on each vehicle, releasing them at the same instant. Record the time for the vehicles to
meet. Perform two trials and take the average value as your accepted time.
3. Make a graph of “Closing Distance vs. Time” for this procedure. Determine the equation of the
line that best fits these data points. The slope of this line will be the relative velocity (speed)
of the two vehicles as they approach each other from opposite directions.
Closing
Distance, m
0.0
0.5
1.0
1.5
2.0
2.5
3.0
Time, seconds
Trial 1
0
Trial 2
0
Average Time,
seconds
0
2
CMSE Phys
Relative Velocity (Speed) as Vehicle Approaches from Behind
Procedure continued:
4. Now place the vehicles facing the same direction the distance apart indicated in the table.
The faster vehicle should be the indicated distance behind the slower one.
5. Turn on each vehicle, releasing them at the same instant. Record the time for the faster
vehicle to catch up to the slower one. Perform two trials and take the average value as your
accepted time.
6. Make a graph of “Closing Distance vs. Time” for this procedure. Determine the equation of the
best fit line for these data points. The slope of this line will be the relative velocity (speed) of
the two cars as the faster vehicle approaches the slower one from behind.
Closing
Distance, m
0.0
0.20
0.40
0.60
0.80
1.00
1.20
Time, seconds
Trial 1
0
Trial 2
0
Time, seconds
0
Questions:
1.
Compare your experimental relative speeds with the estimates you made earlier.
2. Do you think your method of calculating relative speeds (addition or subtraction of speeds) is
always valid regardless of the speeds of the two objects? ______
Comment on your answer.
3. List possible sources of error in this lab.
3
CMSE Phys
Graph s of Moti on in One Di mensi on
Purpose:
to examine and compare the shapes of
position-time and velocity-time graphs
for objects moving in one dimension
Procedure:
Use the simulation at the web site
http://jersey.uoregon.edu/vlab/block/Block.html
to complete the summary table illustrating
shapes of graphs for objects experiencing
one-dimensional motion.
Use the knowledge you gain from this simulation and class discussion to complete the parts of
the table illustrating motion that the simulation will not run.
Initial Position
Initial Velocity
Acceleration
0
Positive
0
0
Negative
0
0
0
Positive
0
0
Negative
Positive
0
Positive
Positive
0
Negative
Sketch of
Position-Time Graph
Sketch of
Velocity-Time Graph
1
CMSE Phys
Initial Position
Initial Velocity
Acceleration
Negative
0
Positive
Negative
0
Negative
0
Positive
Positive
0
Positive
Negative
0
Negative
Positive
0
Negative
Negative
Positive
Positive
0
Positive
Negative
0
Negative
Positive
0
Negative
Negative
0
Positive
Positive
Positive
Sketch of
Position-Time Graph
Sketch of
Velocity-Time Graph
2
CMSE Phys
Initial Position
Initial Velocity
Acceleration
Positive
Positive
Negative
Positive
Negative
Positive
Positive
Negative
Negative
Negative
Positive
Positive
Negative
Positive
Negative
Negative
Negative
Positive
Negative
Negative
Negative
0
0
0
Negative
0
0
Positive
0
0
Sketch of
Position-Time Graph
Sketch of
Velocity-Time Graph
3
CMSE Phys
Questions:
1. What is indicated by a velocity-time graph that crosses the x-axis?
2. How can you tell by looking at a position-time graph whether or not the object was
changing speed?
3. How can you tell by looking at a velocity-time graph whether or not the object was
changing speed?
4. What is the effect of changing the initial position on position-time and velocity-time
graphs?
5. What is represented by the y-intercept on a position-time graph?
6. What is represented by the y-intercept on a velocity-time graph?
7. What is represented by an x-intercept on a position-time graph?
8. What is represented by an x-intercept on a velocity-time graph?
9. No matter what the initial position and initial velocity are, the velocity-time graph of an
object with a positive acceleration will always …
10. No matter what the initial position and initial velocity are, the velocity-time graph of
an object with a negative acceleration will always …
11. No matter what the initial position and initial velocity are, the velocity-time graph of
an object with no acceleration will always …
4
CMSE Phys
Accel era tion Do wn an Incli ne
There is a well-known story that Galileo dropped two objects of different
weights from the Leaning Tower of Pisa in order to show that all objects
accelerate toward the Earth at the same rate, regardless of their weight
as long as air resistance is negligible. Historians, however, are quite
certain that Galileo never performed such an experiment.
Galileo’s experiments with acceleration involved rolling balls down an inclined plane. He did this out
of necessity because of hi s inability to make precise measurements of the small distances and short
time intervals needed for measuring the acceleration of objects in free fall. The inclined plane’s
angle could be adjusted until the time for the ball to roll to the end was long enough for even the
crude time -measuring devices of his day to produce useful results.
In this exercise, you will examine acceleration by measuring the time needed for an object to roll
various distances down an inclined plane – much like Galileo did around 400 years ago.
Purpose:
1. Examine the acceleration of a object rolling down an inclined plane
2. Determine the shape of a “Distance vs Time” graph for an accelerating object
3. Determine the mathematical relationship between the distance and time an object travels
while it is accelerating
Materials:
inclined plane, marble, stopwatch, meter stick or measuring tape
Procedure:
1.
2.
3.
4.
5.
6.
7.
Measure and mark from one end of the inclined plane the distances indicated in the data
table.
Place your inclined plane on something (a book?) so that one end is slightly elevated.
Use the stopwatch to determine how much time is needed for the marble to roll each
indicated distance down the incline. Record this time in the data table.
Perform three time trials for each distance and average them.
Use MS Excel to make a graph of “Distance vs Time.”
Use the MS Excel “Add Trendline” function to draw and calculate the best-fit curve to your
data points. Place this on your graph.
Answer the questions at the end of this activity.
1
CMSE Phys
Distance,
meters
0.10
0.15
0.20
0.40
0.50
0.60
0.70
0.80
0.90
1.20
1.35
1.60
1.80
Trial 1
Time, seconds
Trial 2
Trial 3
Average Time,
seconds
Questions:
1.
How does a “distance vs time” graph of accelerated motion compare with a “distance vs
time” graph of non-accelerated motion (constant velocity)?
2. How can you tell by looking at a “distance vs time” graph whether or not the object has
constant or changing speed?
3. What does the shape of your graph and the “best-fit” equation tell us about the
mathematical relationship between distance and time for a uniformly accelerating object?
4. When looking at his data, Galileo discovered that an object would travel 4 times as far (22 )
in twice the time, 9 times as far (32 ) in triple the time, 16 times as far in (42 ) in quadruple
the time, etc... Use your graph to find the ….
2
CMSE Phys
time
time
time
time
time
time
to
to
to
to
to
to
travel
travel
travel
travel
travel
travel
0.40 m ____
0.60 m ____
0.80 m ____
1.00 m ____
1.20 m ____
1.60 m ____
time to travel 0.10 m ____
time to travel 0.15 m ____
time to travel 0.20 m ____
time to travel 0.25 m ____
time to travel 0.30 m ____
time to travel 0.40 m ____
ratio
ratio
ratio
ratio
ratio
ratio
=
=
=
=
=
=
____
____
____
____
____
____
time to travel 0.90 m ____
time to travel 1.35 m ____
time to travel 1.80 m ____
time to travel 0.10 m ____
time to travel 0.15 m ____
time to travel 0.20 m ____
ratio = ____
ratio = ____
ratio = ____
5. Do your results seem to agree with Galileo’s discovery? _____ Why/Why not?
6. What could you do in order to experimentally test whether or not all objects accelerate at
the same rate, regardless of their weight?
7. How do you think the angle of incline affects this experiment?
8. What should happen to the time values in your data table if the incline is made steeper?
9. What should happen to the ratios in question #4 if the incline is made steeper?
10. List possible sources of error in this lab.
3
CMSE Phys
A ccel era tio n of a Fr eely F allin g Objec t: A Vi rt ual Ac tivity
Purpose:
1. Examine distance-time and velocity-time graphs of a freely falling object.
2. Determine the acceleration due to gravity of an object in "free fall."
Procedure:
1. Go to the web site http://jersey.uoregon.edu/vlab/AverageVelocity/index.html .
2. Complete Data Table I by running the simulation in order to determine through
“trial and error” the distance the object falls during the specified times.
3. Use MS Excel to make a graph of "Total Distance Fallen vs. Time."
4. Use the “Add Trendline” function to determine and place the “best fit” equation
on your graph.
5. Print your graph, making sure it is labeled properly.
6. How can you tell by looking at a position-time graph whether or not the object had a
constant velocity (speed)?
Data Table I
Time, s
Distance,
m
0.0
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40
0.45
0.50
0.55
0.60
0.65
0.70
0.75
0.80
0.85
0.90
0.95
1.00
1.05
1.10
1
CMSE Phys
To find out how the velocity (speed) changed and obtain the acceleration as the object fell, you must first
calculate average velocities (speeds) of specific time intervals. For convenience, you will calculate the average
velocity (speed) during every tenth of a second. You will then see how these speeds changed with time.
5. Subtract distances from Data Table I to find the distances the object fell during every tenth of a second.
Record these distances in Data Table II as Interval Distances.
6. Calculate the average velocity (speed) during each of these intervals using the relationship average speed =
distance/time. The time for each interval will be 0.10 s. Record these values in the data table.
7. Using the assumption that a freely falling object increases its speed uniformly, we can conclude that the average
speed during the interval will equal the instantaneous speed at the time halfway through the interval.
Therefore, the instantaneous velocity (speed) at time t = 0.15 s will be the same as the average velocity (speed)
during the time from t = 0.10 s to t = 0.20 s.
Data Table II
Time Interval, s
Time of Interval, s
0.00 - 0.10
0.10 - 0.20
0.20 - 0.30
0.30 - 0.40
0.40 - 0.50
0.50 - 0.60
0.60 - 0.70
0.70 - 0.80
0.80 - 0.90
0.90 - 1.00
1.00 - 1.10
0.10
0.10
0.10
0.10
0.10
0.10
0.10
0.10
0.10
0.10
0.10
Interval Distance, m
Average Velocity for
Interval, m/s
Avg. Vel. = Inst.
Vel. at Time…, s
0.05
0.15
0.25
0.35
0.45
0.55
0.65
0.75
0.85
0.95
1.05
2
CMSE Phys
8. Use MS Excel and the last two columns in Data Table II to make a graph of “Instantaneous Velocity vs Time.”
9. Use the “Add Trendline” function to determine and place the “best fit” equation on your graph.
10. Print this graph, making sure it is labeled properly.
Discussion Questions:
1. The slope of your “Instantaneous Velocity vs Time” graph should be the value of the object’s acceleration.
The slope of our graph is __________.
2. Make a statement comparing your acceleration to the accepted value of 9.8 m/s/s.
3. Look at the equation for your “Total Distance Fallen vs Time” graph. How can you determine the value of the
gravitational acceleration from that equation?
4. Even though this activity was performed using a computer simulation, your results may not be in exact agreement
with the accepted value for gravitational acceleration.
What are some reasons why an activity such as this might still have error in it?
Extension Idea: Repeat this process simulating free fall on Mars or the Moon.
(not required, but something else that could be done)
3
CMSE Phys
Resul tan t V ect ors
Part I.
Calculate the resultant vectors when the following sets of vectors are combined.
Show all steps as directed in class and illustrated by this example.
A = 40 N @ 30° SE
B = 60 N @ 70° SW
Ax = 40 cos 30° = 34.64
Bx = - 60 cos 70° = - 20.52
Rx =
Ay = - 40 sin 30° = - 20.00
By = - 60 sin 70° = - 56.38
14.12
Ry = - 76.38
R2 = Rx 2 + Ry2 = (14.12)2 + (- 76.38)2 = 6033.28, so R = 77.67 N
T = Tan-1 (Ry/Rx) = Tan-1 (76.38/14.12) = 79.53° SE
Solution: R = 77.67 N @ 79.53° SE
Part II.
Using either the “head-to-tail” or “head-to-head” graphical method, construct the
resultant vectors when these same sets of vectors are combined. Use a scale of
1.0 cm = 1.0 unit. Measure the magnitude and direction of the resultant and
compare with your calculated resultant. Label all vectors as directed in class.
1. A = 35 N @ 60° NE, B = 50 N @ 20° NW
2. A = 70 m/s @ 60° SW, B = 50 m/s @ 70° NW
3. A = 40 m @ 60° SE, B = 80 m @ 30° NW
4. A = 15 lb @ 60° NE, B = 50 lb @ 20° SE
5. A = 35 N @ 40° SW, B = 65 N @ 20° NW, C = 65 N @ 20° NE
6. A = 75 N @ 10° NE, B = 50 N @ 20° NW, C = 65 N @ 70° SE
Softball Throw
The initial velocity of a projectile may be found
by measuring the amount of time it is in the air,
the horizontal distance it travels during that time,
and applying these values to a few simple calculations.
Procedure:
Record the name of the person throwing the softball. Throw the ball and measure the distance, in feet, and the time, in seconds,
the ball travels through the air and record these values in the appropriate place in the data table. Repeat this procedure until this
portion of the data table is complete.
Use the formula d x = vxt to find the horizontal velocity, in ft/s, for each trial. Record these values in the data table.
To find the initial vertical velocity, vy, use the formula vy = gt, where g is the acceleration of gravity and t is the time for the
upward trip of the ball only. Use g = 32 ft/s/s and one-half of the total time in the air. Record these values in the data table.
You now have the horizontal and vertical components of the initial velocity. Use the Pythagorean Theorem (v2 = vx2 + vy2 ) to
calculate the magnitude of the initial velocity in ft/s. Record these values in the data table.
To convert these speeds from ft/s to mph, use the relationship that 1 mile = 5280 feet and 1 hour = 3600 sec. Record these values
in the data table.
Divide the vertical velocity by the horizontal velocity and find the inverse tangent of this result to find the angle above the
horizontal that the ball was thrown. Record these values in the data table.
The maximum height, in feet, the ball traveled above the release point is found by squaring the vertical velocity (in ft/s) and
dividing by twice the acceleration of gravity (2 x 32 ft/s/s = 64 ft/s/s).
1
Data Table
Name
Horizontal
Distance,
feet
Time,
seconds
Horizontal
Velocity,
ft/s
Vertical
Velocity,
ft/s
Velocity,
ft/s
Velocity,
mph
Angle,
θ
Maximum
height,
ft
2
CMSE Phys
Newton’s 2nd Law: Acceleration of a Pulley System
A “Virtual” E xercise
According to Newton’s 2nd Law, the acceleration of an
object is inversely proportional to its total mass and
directly proportional to the net force acting on it.
Go to the web site
http://physics.bu.edu/~duffy/java/Rotation2.html .
You will see a drawing identical to the one to the right.
Run the simulation while adjusting the masses of the red
and blue blocks in order to examine Newton’s Second Law.
For the first trials, you will keep a constant total mass
of 10 kg. By “moving” mass from one side to the other,
you will vary the net force.
1. Run the simulation using the masses shown in Data Table I, using a mass of zero for the pulley.
2. Record the acceleration shown in the simulation.
3. Calculate the weights of the blocks. (Use g = 9.8 m/s/s when calculating the weights.)
4. The net force will be the difference in the weights (Blue weight – Red weight).
5. Make a graph of Acceleration vs Net Force when Total Mass is Constant.
6. Does the shape of your graph confirm the relationship between acceleration and net force that Newton’s Law
predicts?
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CMSE Phys
Data Table I - Experimental Results: Constant Mass
Block Mass, kg
Red
Blue
1
9
2
8
3
7
4
6
5
5
6
4
7
3
8
2
9
1
Total Mass, kg
Block Weight, N
Red
Blue
Net Force, N
Acceleration,
m/s/s
For these next trials, you will keep a constant net force of 9.8 N. By “adding” mass
to each side of the pulley, you can maintain the same net force while varying the
total mass.
1. Run the simulation using the masses shown in Data Table II, using a mass of zero for the pulley.
2. Record the acceleration shown in the simulation.
3. Calculate the weights of the blocks. (Use g = 9.8 m/s/s when calculating the weights.)
4. The net force will be the difference in the weights (Blue weight – Red weight).
5. Use MS Excel to make a graph of Acceleration vs Total Mass when the Net Force is Constant.
6. Does the shape of your graph confirm the relationship between acceleration and total mass that Newton’s Law
predicts?
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CMSE Phys
Data Table II - Experimental Results: Constant Net Force
Block Mass, kg
Red
Blue
1
0
2
1
3
2
4
3
5
4
6
5
7
6
8
7
9
8
Total Mass, kg
Block Weight, N
Red
Blue
Net Force, N
Acceleration,
m/s/s
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CMSE Phys
Newton’s 2nd Law: Mass on Table System
A “Virtual” E xercise
•
•
•
•
Go to the site http://webphysics.ph.msstate.edu/jc/library/4-7a/index.html .
Click on “Start Simulation.”
You will open a window identical to the one shown below.
Run the simulation while adjusting the mass of the wagon and the hanging mass
in order to examine Newton’s Second Law.
•
According to Newton’s 2nd Law, the acceleration of an object is inversely
proportional to its total mass and directly proportional to the net force acting
on it.
Part I:
For the first trials, you will keep a constant total mass of 200 g.
By “moving” mass from the wagon to the hanger, you will vary the net force.
1. Run the simulation using the masses shown in the data table and setting the friction
coefficient to zero.
2. Record the acceleration shown in the simulation. How would you calculate these
values if they were not given to you in the simulation?
3. Calculate the weight of the hanging mass. (Use g = 9.8 m/s/s when calculating this
weight.)
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CMSE Phys
4. Since there is “no friction,” the net force is equal to the weight of the hanging mass.
5. Make a graph of Acceleration vs Net Force when Total Mass is Constant.
6. Does the shape of your graph confirm the relationship between acceleration and net
force that Newton’s 2nd Law predicts?
Experimental Results: Constant Mass
Mass, kg
Wagon
Hanging
0.199
0.175
0.150
0.125
0.100
0.075
0.050
0.025
0.001
0.001
0.025
0.050
0.075
0.100
0.125
0.150
0.175
0.199
Total Mass, kg
Net Force, N
(Weight of the
Hanging Mass)
Acceleration,
m/s/s
0.200
0.200
0.200
0.200
0.200
0.200
0.200
0.200
0.200
Part II:
For these next trials, you will keep a constant net force of 0.49 N (by
keeping a constant mass of 50 g on the hanger). By “adding” mass only to
the wagon, you can maintain this same net force while varying the total mass.
1. Run the simulation using the masses shown in the data table, again setting the
friction coefficient to zero.
2. Record the acceleration shown in the simulation. How would you calculate these
values if they were not given to you in the simulation?
3. Calculate the weight of the hanging mass. (Use g = 9.8 m/s/s when calculating this
weight.)
4. Since there is “no friction,” the net force is the weight of the hanging mass.
5. Make a graph of Acceleration vs Total Mass when the Net Force is Constant.
6. Does the shape of your graph confirm the relationship between acceleration and
net force that Newton’s 2nd Law predicts?
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CMSE Phys
Experimental Results: Constant Net Force
Mass, kg
Wagon
Hanging
0.010
0.030
0.070
0.100
0.150
0.250
0.350
0.500
0.650
0.800
0.900
0.050
0.050
0.050
0.050
0.050
0.050
0.050
0.050
0.050
0.050
0.050
Total Mass, kg
Net Force, N
(Weight of the
Hanging Mass)
Acceleration,
m/s/s
Questions:
1. How would you calculate the acceleration of the system if friction were present?
2. Suppose there is no friction. In order for the wagon on the table to move, the
weight hanging over the side of the table must be at least…
3. Suppose friction is present. In order for the wagon on the table to move, the
weight hanging over the side of the table must be at least….
4. Is it possible to obtain an acceleration equal to the gravitational acceleration if
friction is not present? Why or why not?
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CMSE Phys
The Simple Pendulum
Objectives:
1) To determine if/how mass, length,
and angular displacement affect the
period of a simple pendulum
2) Use a simple pendulum to determine
the acceleration of gravity
Materials: light string, meter stick, stopwatch, various masses
•
•
•
•
Your simple pendulum will consist of a mass suspended by light thread from a point about which it can
freely swing.
The displacement of the pendulum will be the angle at which it is pulled back before release to swing.
The length is the distance from the point of suspension to the center of gravity of the mass.
You will measure the period (the time it takes for the pendulum bob to swing from one side to the other
and back again) while individually varying the mass, length, and angular displacement of the pendulum.
I. DOES MASS AFFECT THE PERIOD OF A PENDULUM?
A. Use a length of string between 0.60 m and 1.20 m. Tie a mass to the string. Pull the pendulum
bob back about 30° and record the time it takes for the pendulum to make 10 complete cycles.
Divide this time by 10 to get the period of the pendulum.
B. Record this information in DATA TABLE I.
C. Now perform the same procedure, but use a different mass. Be sure to keep all other variables
EXACTLY the same as before.
D. Repeat these steps for the other masses. Record all information in the data table.
II. DOES LENGTH AFFECT THE PERIOD OF A PENDULUM?
A. Find the period of the pendulum as you did above, but use the same mass and amplitude in
each trial, while varying only the pendulum’s length.
B. Do this according to DATA TABLE II.
III. DOES AMPLITUDE AFFECT THE PERIOD OF A PENDULUM?
A. This time use a constant length and mass, but vary the amplitude (angle) through which the
pendulum swings.
B. Find the period of the pendulum with initial amplitudes given in DATA TABLE III.
C. Record all information in the data table.
Find the formula for the pendulum in your book and use your results to calculate the acceleration of
gravity for each trial.
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CMSE Phys
DATA TABLE I – Variable Mass
Mass,
g
Length,
m
Amplitude,
deg
Time, s
10 cycles
Period,
s
g,
m/s2
Time, s
10 cycles
Period,
s
g,
m/s2
Time, s
10 cycles
Period,
s
g,
m/s2
20
50
100
200
500
DATA TABLE II – Variable Length
Mass,
g
Length,
m
Amplitude,
deg
0.20 m
0.35 m
0.50 m
0.65 m
0.80 m
0.95 m
1.10 m
1.25 m
1.40 m
DATA TABLE III – Variable Amplitude
Mass,
g
Length,
m
Amplitude,
deg
10
20
30
40
50
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CMSE Phys
Results :
Make a graph of “Period vs Mass” using the results of Data Table I.
Make a graph of “Period vs Length” using the results from Data Table II.
Make a graph of “Period vs Amplitude” using the results of Data Table III.
On each graph, write a statement commenting on the relationship between the period and the manipulated
variable that is indicated by the shapes of the graphs. For example, you may find relationships that are
directly proportional, inversely proportional, quadratic, square root, sinusoidal, or you may find no
relationship at all.
Write a summary paragraph describing what you learned about pendulums from this activity.
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CMSE Phys
Sliding Friction
Objectives:
• determine the coefficient of sliding friction for wood on desk ,
rubber-soled shoe on dry floor, and rubber-soled shoe on wet floor
• determine the relationship between friction force and surface area
Equipment: force scale, friction block, shoe, various masses, water
Procedure:
“Wood on Desk - Wide Side”
1. Find the weight of your friction block using either the triple beam balance or your force scale.
2. Record the weight of the friction block in Data Table I.
3. Attach the force scale to the friction block and pull the scale horizontally with the desktop at a steady rate and record
the average force reading in your data table under the column “Friction Force.”
4. Add some mass. Calculate this additional weight (use g = 10 m/s/s for each of the calculations) and record your findings
in the Data Table. This total amount of weight will be known as the “Normal Force.”
Pull the block as before to find the amount of friction force with this total weight.
5. Continue until Data Table I is completed with 5 total trials.
6. Calculate the “Friction Coefficient” by dividing the Friction Force by the Normal Force.
This coefficient has no units since you are dividing Newtons by Newtons.
7. Find the average value of your friction coefficients and record beneath your data table.
8. Make a graph of “Friction Force vs. Normal Force.” Include the origin as one of your data points. Determine the best fit
equation of your line and record on the graph. Notice how close the slope is to your average Friction Coefficient.
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CMSE Phys
“Rubber-soled Shoe on Dry Floor”
9. Repeat procedures 1-8 using the shoe on the dry floor for
Data Table II – “Rubber-soled Shoe on Dry Floor.”
Data Table I – “Wood on Desk - Wide Side”
Trial
Block Weight,
N
1
2
3
4
5
Additional
Mass,
kg
0
Additional
Weight,
N
0
Normal Force
(Total Weight)
N
Friction
Force,
N
Friction
Coefficient
Average Friction Coefficient for “Wood on Desk” = __________
Data Table II – “Rubber-soled Shoe on Dry Floor”
Trial
1
2
3
4
5
Shoe Weight,
N
Additional
Mass,
kg
0
Additional
Weight,
N
0
Normal Force
(Total Weight)
N
Friction
Force,
N
Friction
Coefficient
Average Friction Coefficient for “Rubber-soled Shoe on Dry Floor” = __________
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CMSE Phys
10. Repeat procedures 1-8 using the shoe on a place where you have made the floor wet. Record the results in Data Table
III – “Rubber-soled Shoe on Wet Floor.”
Data Table III – “Rubber-soled Shoe on Wet Floor”
Trial
1
2
3
4
5
Shoe Weight,
N
Additional
Mass,
kg
0
Additional
Weight,
N
0
Normal Force
(Total Weight)
N
Friction
Force,
N
Friction
Coefficient
Average Friction Coefficient for “Rubber-soled Shoe on Wet Floor” = __________
Compare the friction coefficient of rubber on a dry floor with rubber on a wet floor.
You will now repeat these procedures for finding the friction coefficient for wood on desk, but will use the “thin side” of the wood
block. Since the “wide side” has approximately ______ times as much area as the “thin side,” most people would expect the
friction on the “wide side” to be about _____ times as large.
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CMSE Phys
11. Perform these trials as before and record your results in Data Table IV - “Wood on Desk - Thin Side.”
Data Table IV – “Wood on Desk – Thin Side”
Trial
Block Weight,
N
1
2
3
4
5
Additional
Mass,
kg
0
Additional
Weight,
N
0
Normal Force
(Total Weight)
N
Friction
Force,
N
Friction
Coefficient
Average Friction Coefficient for “Wood on Desk – Thin Side” = __________
Questions:
1. How does the friction coefficient depend on the area of the surface in contact?
2. Why do you think this is so?
3. What factors do influence the amount of sliding friction?
4. Name some possible sources of error in this lab.
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CMSE Phys
Data Table V – “
Trial
Block Weight,
N
1
2
3
4
5
Additional
Mass,
kg
0
Additional
Weight,
N
0
1
2
3
4
5
Block Weight,
N
Additional
Mass,
kg
0
”
Normal Force
(Total Weight)
N
Average Friction Coefficient for “
Data Table VI – “
Trial
on
Friction
Force,
N
on
on
Additional
Weight,
N
0
” = __________
”
Normal Force
(Total Weight)
N
Average Friction Coefficient for “
Friction
Coefficient
Friction
Force,
N
on
Friction
Coefficient
” = __________
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CMSE Phys
Forces in Equilibrium
According to Newton’s First Law of Motion, an object remaining at rest even when
forces are acting upon it does so because there is no net force acting on the object.
This means that the resultant or vector sum of all the forces acting on the object is zero.
An object in this state or condition is said to be “in equilibrium.”
In this lab exercise, you will apply forces to an object in such a way that the object
remains stationary. You will then verify that the resultant force is indeed zero.
1. Place the ring (washer) over the origin of your
polar grid paper with the force scales attached
in the positions indicated in the data table.
2. Pull each scale in the indicated directions. Pull so
that the ring remains centered over the origin. At
least one of your forces should be over 15.0 N.
3. Record the reading on each scale. Record to the nearest tenth of a Newton when using these
0-20 N scales.
4. Calculate the horizontal (x) and vertical (y) components of each force.
5. Sum the components. Record these values in the data tables.
6. Use the Pythagorean Theorem and the inverse tangent function to calculate each resultant
force’s magnitude and direction. Your resultant magnitudes should be close to zero.
A
B
C
Force
(Newtons)
Angle
(Degrees)
0 (East)
110 (70° NW)
200 (20° SW)
Sum of Components =
Horizontal
Component
Vertical
Component
Force
(Newtons)
Horizontal
Component
Vertical
Component
Resultant =
A
B
C
Angle
(Degrees)
45
135 (45° NW)
270 (South)
Sum of Components =
Resultant =
1
CMSE Phys
Force
(Newtons)
A
B
C
Angle
(Degrees)
80
210 (30° SW)
280 (80° SE)
Sum of Components =
Horizontal
Component
Vertical
Component
Angle
(Degrees)
60
190 (10° SW)
340 (20° SE)
Horizontal
Component
Vertical
Component
Angle
(Degrees)
25
180 (West)
335 (25° SE)
Horizontal
Component
Vertical
Component
Resultant =
Force
(Newtons)
A
B
C
Sum of Components =
Resultant =
Force
(Newtons)
A
B
C
Sum of Components =
Resultant =
A
B
C
D
E
Join with another group for this final trial.
Force
Angle
Horizontal
(Newtons)
(Degrees)
Component
0 (East)
20
120 (60° NW)
240 (60° SW)
315 (45° SE)
Sum of Components =
Vertical
Component
Resultant =
2
CMSE Phys
Graph constructed using a free graphing program found at
http://www.mathematicshelpcentral.com/graph_paper.htm
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CMSE Phys
Torque and Rotational Equilibrium
In this lab, you will pull on a meter stick at various locations until the meter stick is “at rest” (neither
translating nor rotating, which is a state of equilibrium). You will then verify the two conditions for
equilibrium by examining the total amounts of upward and downward force and the total amounts of
clockwise and counterclockwise torques.
1.
Place the scales at the locations indicated. Scales A and C
should pull in the same direction, with scale B (and D if given)
pulling in the opposite direction. Place arrows on the meter
stick diagram in order to show the location of each force.
2. Record the readings on each scale when equilibrium is achieved.
3. Use the “zero” end of the meter stick as your pivot point and
calculate your torques (in this lab, “torque = force x location” since the location is the distance
from the zero end).
4. Sum the forces and torques. Look at each of these values to see how well each trial verified the
conditions for equilibrium.
I.
Scale
A
B
C
Location,
cm
20
50
80
Force,
N
Up or Down?
Torque,
N•cm
0 cm
cw or ccw?
100 cm
Σ Fup
Σ Fdown
Σ τcw
Σ τccw
II.
Scale
A
B
C
Location,
cm
30
60
90
Force,
N
Up or Down?
Torque,
N•cm
0 cm
cw or ccw?
100 cm
Σ Fup
Σ Fdown
Σ τcw
Σ τccw
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CMSE Phys
III.
Scale
A
B
C
Location,
cm
10
70
90
Force,
N
Up or Down?
Torque,
N•cm
0 cm
cw or ccw?
100 cm
Σ Fup
Σ Fdown
Σ τcw
Σ τccw
IV.
Scale
A
B
C
D
Location,
cm
25
40
70
80
Force,
N
Up or Down?
Torque,
N•cm
0 cm
cw or ccw?
100 cm
Σ Fup
Σ Fdown
Σ τcw
Σ τccw
V.
Scale
A
B
C
D
Location,
cm
5
50
70
85
Force,
N
Up or Down?
Torque,
N•cm
0 cm
cw or ccw?
100 cm
Σ Fup
Σ Fdown
Σ τcw
Σ τccw
2
CMSE Phys
POWER
A simple way to measure the power output of a
person is to measure the time it takes the person
to walk/run up a flight of stairs (or bleachers).
In this experiment you will measure your power in
climbing a flight of stairs and compare it to the
power of your classmates.
1. Measure the height from the ground to the second floor/top of stairs (or other desired position).
2. Record your name and weight (in pounds) or use the scale to obtain your mass (in kilograms).
3. Measure the time it takes to run (or walk) to the desired height.
4. Share your values with your classmates and record their values in the data table.
After everyone has run (or walked) up the stairs, perform the following calculations to find the power.
1. Convert a weight from pounds to Newtons by dividing the weight in pounds by 2.2 to get the mass in kilograms.
Then multiply the mass (in kilograms) by 9.8 m/s/s to obtain the weight in Newtons.
2. Find the amount of work (in Joules) each person has done by multiplying their weight (in Newtons) by the height
ascended (in meters).
3. Find the power (in Watts) using the formula: Power (W) = Work (J) / time (sec).
4. Find the equivalent horsepower by dividing the power (in Watts) by 746 because 1 horsepower equals 746 Watts.
5. Record all values in the data table.
1
CMSE Phys
**** Alternative Procedure ****
Find the power output in doing work on an object (a brick, book bag, etc...). Weigh the object and carry it up the
stairs or pull it up using a rope. Calculate the power exactly as described above. In the data table, write “your name
carrying or lifting item” under the “Name” column.
Questions:
1. The work done in traveling up the flight of stairs (or lifting an object) depends only on …
2. Power depends on …
3. How would the work done in lifting a load up three flights of stairs compare to the work done in lifting the same load up
one flight of stairs?
4. What happens to the power output if the same amount of work is done in one-half the time?
5. What happens to the power output if the same amount of work is done in twice the time?
6. How much work (energy) is needed to keep a 100 W light bulb lit each second?
7. How much work (energy) is needed to keep a 100 W light bulb lit each minute?
8. How much work (energy) is needed to keep a 100 W light bulb lit each hour?
9. The same amount of work (energy) needed to keep the 100 W light bulb lit for one hour could be used to lift a 2000 kg
SUV to what height?
2
CMSE Phys
POWER DATA TABLE
Name
Weight
(lbs)
Mass
(kg)
Weight
(N)
Height
(meters)
Work
(Joules)
Time
(sec)
Power
(Watts)
Power
(hp)
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CMSE Phys
Wave Modeling
Purpose:
•
•
model transverse and longitudinal waves
identify and measure wave characteristics
Materials:
•
“butcher” paper ( 5-7 feet long, 2-3 feet wide), stopwatch, meter stick, markers
Procedure:
Each group should have three members.
Place the large sheet of butcher paper on the lab table.
One group member steadily pulls the paper across the table while another member moves
the marker back and forth over the paper. The arm should swing freely as a pendulum.
The third group member uses the stopwatch to measure the amount of time needed to
sketch the wave motion across the entire length of paper.
A transverse wave may be modeled when the marker moves back and forth perpendicularly
to the direction of the moving paper. A longitudinal wave may be modeled when the
marker moves back and forth across the paper parallel to its direction of movement. If
done carefully, you should see nice consistent shapes for these two wave models.
For each of these two wave models:
•
•
•
•
•
•
•
Record the total time of the wave motion on the paper.
Label, measure, and record the wavelength of the wave.
Label, measure, and record the amplitude of the wave.
Count the number of complete vibrations and divide by the total time to obtain
the frequency of the wave.
Divide the total time by the number of complete vibrations to obtain the period
of the wave.
Find the wave’s velocity by measuring the total distance the wave traveled and
dividing this value by the total time.
Now calculate the wave’s velocity by multiplying the recorded frequency of the
wave by the measured wavelength. Compare this result with the velocity
obtained using the total distance and time.
Show all work and calculations on the butcher paper.
CMSE Phys
PULSES ON A COIL SPRING
Coiled springs are excellent materials for
analyzing a variety of wave behaviors. In
this activity, you will examine transverse and
longitudinal pulses, fixed- and free-end
reflections, constructive and destructive
interference, standing waves, and the
behavior of waves when they reach new
transmitting media.
TRANSVERSE PULSES
A. Send a transverse pulse down a stretched large coil spring. Observe the motion of the
spring’s coils. Draw a sketch of the pulse traveling down the spring.
Why is this pulse called a transverse pulse?
B. Observe the speed of the pulse while varying the pulse amplitude. What happens to the
speed of the pulse as the amplitude changes?
C. Observe the speed of the pulse while varying the tension in the spring. What do you notice
about the pulse speed with respect to changes in tension?
D. Does the stretched spring under different tensions represent the same or different
transmitting media?
E. Maintain a constant tension and send continuous wave trains of varying frequencies down
the spring. What happens to the wavelength as the frequency increases?
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CMSE Phys
WAVE INTERFERNCE
F. Send two pulses of approximately the same amplitude from opposite ends of the spring
toward each other on the same side of the spring. What do you observe?
Do the two disturbances “bounce off” each other or pass right through each other?
What do you notice when the pulses “overlap”?
Draw sketches showing the pulses, labeled “A” and “B”, before, during, and after they
meet.
G. Send two pulses of approximately the same amplitude from opposite ends of the spring
toward each other on opposite sides of the spring. What do you observe?
Do the two disturbances “bounce off” each other or pass right through each other?
What do you notice when the pulses “overlap”?
Draw sketches showing the pulses (labeled “A” and “B”) before, during, and after they
meet.
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CMSE Phys
WAVE REFLECTION
H. Hold the spring firmly down in place at the far end and send a pulse down the spring.
Describe and illustrate your observations of reflection from this “fixed end.”
I. Attach and hold a light string on one end of the spring and send a pulse from the other
end. Describe and illustrate your observations of reflection from this “free end.”
WAVE BEHAVIOR AT MEDIA BOUNDARIES
J. Attach the two springs together and send a pulse from the large spring. Record your
observations.
K. What happens to the wave speed when the pulse goes from the large spring to the small
spring?
.…from the small spring into the large spring?
L. Did you notice any reflection when the pulse reached the junction where the two springs
were connected?
Did more of the wave seem to be transmitted or reflected?
Think of a common example where light waves partially reflect and partially transmit when
they reach the boundary of the transmitting media.
3
CMSE Phys
STANDING WAVES
M. While holding one end of the large spring firmly in place, move the other end of the spring
continuously back and forth to send a continuous wave train down the spring. Adjust your
frequency until a standing wave with two “loops” is obtained.
Now change your frequency of vibration until more loops are formed. Since the speed of
the wave remains constant (do you know why?), shaking the spring with a higher frequency
does what to the wavelength?
In order to obtain standing waves with more loops when the speed of the wave is constant,
what must be done to the frequency of vibration?
How could you determine the wavelength of the wave when a standing wave pattern is
observed?
Draw sketches of standing waves having one, two, three, and four loops. Indicate on your
sketches how the wavelength could be measured.
LONGITUDINAL PULSES
N. Stretch the large spring and send a longitudinal pulse down the spring. Observe the
motion of the spring coils. Draw a sketch of the pulse traveling down the spring.
Why is this pulse called a longitudinal pulse?
Note:
Wave properties such as diffraction and refraction unfortunately cannot be
observed with coiled springs.
4
CMSE Phys
Waves in a Ripple Tank: A Virtual Activity
Go to the site http://www.falstad.com/oscgrid/ . A “Ripple Tank Applet” window
will open that runs a simulation of waves generated in a ripple tank.
By “clicking on” any or all of the three task bars in the upper right hand corner of
the applet window, you can change the type and number of wave sources. The third
task bar allows you to use the mouse to edit the waves or walls (barriers). You can
adjust the speed, resolution, frequency, brightness, and/or damping of the wave
simulation to obtain a clearer representation of the wave phenomena. A complete
and detailed set of directions for how to use this simulation is linked to the web
page.
Your task is to use this web site to identify and investigate various wave properties
and characteristics. You will hand in pictorial representations of…
1. Circular Wave
a. long wavelength
b. shorter wavelength
2. Plane Wave
a. long wavelength
b. shorter wavelength
3. Reflection
a. Plane Wave Off Angled Straight Barrier
b. Plane Wave Off Concave (Parabolic) Barrier
c. Circular Wave Off Straight Barrier
1
CMSE Phys
4. Diffraction
a. Plane Wave Around a Barrier
b. Plane Wave Through an Opening
c. Circular Wave Around a Barrier
d. Circular Wave Through an Opening
5. Refraction of a Plane Wave
6. Refraction due to Temperature Gradient (simulates sound wave over lake)
7. Interference
a. Two Circular Waves (wide spacing between sources)
b. Two Circular Waves (closer spacing between sources)
c. One Plane and One Circular Wave (this is a tricky one to simulate!)
d. Single Slit (plane wave)
e. Double Slit (plane wave)
f. Triple Slit (plane wave)
8. Doppler Effect
9. Beats
10. Something else you find really interesting
You have two options for completing this assignment:
1. Make small (about 4 in. x 4 in.) sketches with colored pens/pencils…OR…
2. Use a “screen capture” program to copy and paste the actual images from
the applet window into a document (MS Word with text boxes, for example),
which can then be saved and printed.
You can download a free trial version of an easy to use screen capture program at
http://www.etrusoft.com/ . The image shown on this handout was “captured” using
this program.
You can probably fit 6 diagrams/sketches on each side of a page. Be sure to label
each sketch.
2
CMSE Phys
Resonance: The Speed of Sound – Closed Tube
Trial
Tuning Fork
Frequency,
Hz
Resonant
Tube Length,
m
Tube
Diameter,
m
Wavelength,
m
Experimental
Speed of Sound,
m/s
Air
Temp,
°C
Accepted
Speed of Sound,
m/s
Percent
Error,
%
1
2
3
4
FOR EACH TRIAL
1. Calculate the wavelength of each resonant sound wave.
Show the formula and calculations in the space below.
2. Calculate the experimental speed of sound.
Show the formula and calculations in the space below.
3. Use the air temperature to find the accepted speed of sound.
Show the formula and calculations in the space below.
4. Calculate the % error for each speed of sound trial. Show the formula and calculations in the space below.
1
CMSE Phys
You will now use the phenomenon of resonance to
determine the frequency of an unmarked tuning fork.
Trial
Resonant
Tube Length,
m
Tube
Diameter,
m
Wavelength,
m
Air Temp,
°C
Accepted
Speed of Sound,
m/s
Calculated
Tuning Fork
Frequency,
Hz
1
2
FOR EACH TRIAL
1. Find the resonant tube length and calculate the wavelength of each resonant sound wave. Show the formula and calculations
in the space below.
2. Use the air temperature to find the accepted speed of sound.
Show the formula and calculations in the space below.
3. Use the experimental wavelength and temperature-based accepted speed of sound to calculate the frequency of your tuning
fork. Show the formula and calculations in the space below .
4. List sources of error in this lab.
2
CMSE Phys
PALM PIPES
Materials:
½ inch PVC pipe cut to the lengths listed below. The pipes can be
marked with permanent marker or fingernail polish. The students
hold the pipe in one hand and strike one of the open ends on the
palm of the other hand, producing the pitch which corresponds to
the length of the pipe.
Note
A
Bb (A#)
B
C
C# (Db)
D
D# (Eb)
E
F
F# (Gb )
G
Ab (G#)
A
Bb (A#)
B
C
C# (Db)
D
D# (Eb)
E
F
F# (Gb )
G
Ab (G#)
Length
*(cm)
38.5
36.4
34.3
32.3
30.5
28.8
27.1
25.6
24.1
22.7
21.4
20.2
19.0
17.9
16.9
15.9
15.0
14.1
13.3
12.5
11.8
11.1
10.5
9.8
Frequency
**(Hz)
220
233
247
261.5
277
293.5
311
329.5
349
370
392
415.5
440
466
494
523
554
587
622
659
698
740
784
831
* Lengths of these pipes are based on an air temperature of 20° C and 0.5 in diameter.
** Frequencies taken from http://ptolemy.eecs.berkeley.edu/eecs20/week8/scale.html
Adapted and expanded from an activity presented by Hugh Henderson of Plano (Texas)
Senior High School at the 2003 AP Physics Institute, Texas A&M University.
1
CMSE Phys
MUSICAL SCALES
Tonic
C
W
D
Third
E
Fourth
F
Fifth
G
Sixth
A
H
B
Tonic
C
C#
D
D#
D#
E
F
F
F#
G
F#
G
G#
G#
A
A#
A#
B
C
C
C#
D
C#
D
D#
E
F
F#
F#
G
G#
G#
A
A#
A
A#
B
B
C
C#
C#
D
D#
D#
E
F
E
F
F#
G
G#
A
A
A#
B
B
C
C#
C
C#
D
D
D#
E
E
F
F#
F#
G
G#
G
G#
A
A#
B
C
C
C#
D
D
D#
E
D#
E
F
F
F#
G
G
G#
A
A
A#
B
A#
B
C
Musical scales and chart taken from
http://www.geocities.com/jayatea.geo/piano.html
TWINKLE, TWINKLE LITTLE STAR
(Nearly the same tune as the “Alphabet Song”)
Twin - kle, twin - kle lit - tle star, How I won - der what you are
Melody:
F
F
C
C D
D C Bb Bb A
A G G F
Harmony: C
C A
A Bb Bb A G G F
F
E
E C
Melody:
Harmony:
Up a - bove the world so high, Like a dia - mond in the sky,
C C
Bb Bb A A G
C C Bb
Bb A A G
A A
G
G F
F C
A A G
G F F C
Melody:
Harmony:
Twin - kle, twin - kle lit - tle star, How I won - der what you are
F
F
C
C D
D C Bb Bb A
A
G G F
C
C
A
A Bb Bb A G G F
F
E
E C
2
CMSE Phys
HAPPY BIRTHDAY
Hap - py birth - day to you, hap - py birth - day to you;
C
C D
C F E C
C D
C G F
Hap - py birth - day dear Ein - stein;
C
C C
A F
E
D
Hap - py birth - day to you!
Bb Bb A
F G F
LONDON BRIDGE
Lon - don bridge is fall - ing down, fall - ing down, fall - ing down;
G
A
G
F E
F
G
D
E
F
E
F
G
Lon - don bridge is fall - ing down, my fair la - dy.
G
A
G
F E
F
B
D G E
C
ROW, ROW, ROW YOUR BOAT
Row, row, row your boat gen - tly down the stream;
C C
C
D
E E
D
E
F
G
Mer - ri - ly, mer - ri - ly, mer - ri - ly, mer - ri - ly,
C
C C G
G G E
E E C
C C
Life is but a dream.
G F E D C
WHERE IS PINKY (POINTER, ETC…)
(or Are You Sleeping?)
“Where is Pin - ky? Where is Pin - key?” “Here I am! Here I am!”
C D E
C
C D E
C
E F G
E F G
“How are you to - day sir?” “Ver - y well I thank you.”
G A G F
E C
G
A G F E
C
Run a - way, run a - way.
C G
C
C G
C
3
CMSE Phys
SINGING CHIMES
(adapted from Taylor, Poth, & Portman (1995), Teaching Physics with TOYS,
Terrific Science Press: Middleton, Ohio. pp. 275-281)
Chimes cut from 4 five-foot pieces of ½ inch aluminum pipe. Total cost of less than $8.00
(purchased as 2 ten-foot sections, Lowe’s Home Building Store, December 2003).
Table 1: Chime Lengths
Cut from pipe 2
Cut from pipe 3
Cut from pipe 1
Cut from pipe 4
Chime #
Length (cm)
Chime #
Length (cm)
Chime #
Length (cm)
Chime #
Length (cm)
1
2
3
4
38.5
37.5
36.2
35.1
5
6
7
17
18
34.2
33.1
32.2
23.8
23.1
8
9
10
11
12
31.1
30.3
29.7
28.9
28.1
13
14
15
16
19
20
27.2
26.3
25.5
24.7
22.5
21.8
p. 276
Table 2: Chime Frequencies
Chime #
1
2
3
4
5
6
7
p. 279
Note
Frequency
(Hz)
Chime #
Note
Frequency
(Hz)
Chime #
Note
Frequency
(Hz)
F
F#
G
G#
A
A#
B
175
185
196
208
220
233
247
8
9
10
11
12
13
14
C
C#
D
D#
E
F
F#
262
277
294
311
330
349
370
15
16
17
18
19
20
G
G#
A
A#
B
C
392
415
440
466
494
523
4
CMSE Phys
SINGING CHIMES SONG SH EET
(musical scores taken from Teaching Physics with TOYS, pp 280-281)
MICHAEL ROW THE BOAT ASHORE
Mi - chael row the boat a - shore
10
14 17 14 17 19
17
10 14 10 14 15
14
Mi - chael row the boat a - shore
D
F# A F# A B
A
D F# D F# G
F#
Hal - le - lu - a
14
17 19 17
10
14 15 14
Hal - le - lu - a
F#
A
B A
D
F# G F#
Mi - chael row the boat a - shore
14
17 17 14 15 14
12
10
14 14 10 12 10
9
Mi - chael row the boat a - shore
F#
A A F# G F#
E
D
F# F# D E D
C#
Hal - le - lu - u - u - a
10
12 14 5 12 10
7
9 10
9
Hal - le - lu - u - u - a
D
E F# A E D
B C# D
C#
HAPPY BIRTHDAY
Hap - py birth - day
8
8
10
8
6
C
C D
C
A#
to
13
8
F
C
Hap - py birth - day
8
8 20
17
17
13
13
8
C
C C
A
A
F
F
C
dear Ag - gie;
13 12
10
8
8
6
F
C
you, hap - py birth - day to
12
8
8
10
8 15
6
6
8
E C
C D
C G
A#
A#
C
E
C
you;
13
8
F
C
D
A#
Hap - py birth - day to you!
18
18 17
13 15 13
13
13 13
8 12 8
10
10
8
8
A#
A# A
F G F
F
F F
C E C
D
D C
C
5
CMSE Phys
Plane Mirror Images
Pre-Lab: Each group must complete and hand in their Pre-Lab Predictions before
obtaining materials for this investigation.
Learning Tasks:
1. Use the available resources (large plane mirror, text, computer simulation, peer counsel)
to determine a plane mirror’s a) minimum length and b) vertical placement on a wall
necessary for one to see a full length image when standing in front of the plane mirror.
2. Determine if/how this necessary mirror size and placement depends on an
individual person’s height and distance away from the mirror.
3. Include a complete explanation of your solutions using the behavior of
light to justify your answers. This explanation should include diagrams.
4. Hand in your group’s report and the Self-Evaluation Rubric.
Resources:
large plane mirrors, text, peer counsel, meter sticks,
computer simulation at
http://www.phy.ntnu.edu.tw/java/optics/mirror_e.html
1
CMSE Phys
Lab Report Self-Evaluation Rubric
Report Objectives
“The report contains acceptable statements describing …”
disagree
unsure
agree
disagree
unsure
agree
disagree
unsure
agree
disagree
unsure
agree
… the minimum length of a plane mirror that is needed for a person to see one’s full length image
… the mirror’s precise placement on the wall in order to see a full length image
… how the mirror’s size and placement depends on the height of the viewer
… how the mirror’s size and placement depends on how far the viewer is from the mirror
Report Objectives
“The report contains acceptable explanations for …”
… why the stated minimum mirror size is valid
… why the stated mirror placement is valid
… why the stated relationship about mirror size, placement, and viewer’s height is valid
… why the stated relationship about mirror size, placement, and viewer’s distance from mirror is valid
Report Objectives
“The report contains correctly drawn and properly labeled ray di agrams
that aid in the description and explanation of…”
… why the stated minimum mirror size is valid
… why the stated mirror placement is valid
… why the stated relationship about mirror size, placement, and viewer’s height is valid
… why the stated relationship about mirror size, placement, and viewer’s distance from mirror is valid
Lab Objectives
“Everyone in our lab group can now…”
… give the minimum length of a plane mirror and its precise placement on the wall for a person of a given
height to see a full length image when standing a designated distance in front of the mirror
… justify why their response to the above is valid
2
CMSE Phys
Plane M ir ror Imag es: P re-L ab P redi cti ons
To be given out in class.
3
CMSE Phys
Curved Mirror Ray Diagrams
Calculate the image distance and size for each case. Enter these values in the data
table.
Using unlined paper in a landscape orientation, draw ray diagrams in order to find
the image of each 2.0 cm object. Use a compass to accurately depict the
curvature of each mirror. Label the focus “F” and center of curvature “C.” Draw
three rays (through or toward focus and parallel, parallel and through or away from
focus, and through the center of curvature) if possible. Measure the image size
and distance. Record these values in the data table and compare with the
calculated.
On your diagrams, classify each image as 1) REAL or VIRTUAL, 2) UPRIGHT or
INVERTED, and 3) REDUCED, ENLARGED, or SAME SIZE.
Lens
Concave
Concave
Concave
Concave
Concave
Convex
Convex
Convex
Convex
Convex
Object
Distance
18.0 cm
12.0 cm
9.0 cm
6.0 cm
3.0 cm
15.0 cm
10.0 cm
7.0 cm
4.0 cm
1.0 cm
Object
size
2.0 cm
2.0 cm
2.0 cm
2.0 cm
2.0 cm
2.0 cm
2.0 cm
2.0 cm
2.0 cm
2.0 cm
Focal
Length
6.0 cm
6.0 cm
6.0 cm
6.0 cm
6.0 cm
-5.0 cm
-5.0 cm
-5.0 cm
-5.0 cm
-5.0 cm
Calculated
di
si
Measured
di
si
***Notice that the focal length of a convex mirror is negative.***
CMSE Phys
Measuring the Index of Refraction
I. Glass/Plastic/Acrylic Rectangle and/or Triangle
1. Place the rectangle/triangle on the center of your paper. Trace around it.
2. Place one pin on either side of the object, snugly up against the sides.
Rectangle: They should not be directly across from one another.
Triangle: They should be directly across from one another.
(Pins A and B in diagrams)
3. Look through the objects until these two pins line up in your eyesight.
4. Place another pin (C) between your eye and the two pins that are lined up in
sight. Now all three pins (A, B, and C) should seem to be lined up.
5. Place a fourth pin (D) on the other side of the object in line with the other
three. You should see all four pins lined up when you look through the
object.
6. Remove the object and pins.
7. Connect the pin holes to show the path of light traveling through the
rectangle/triangle.
8. With your ruler, carefully draw a dotted line “normal” to the object’s
surface where the light ray enters the object. Draw another one where the
light ray leaves the object.
9. Measure the angles of incidence and refraction where the light enters and
where the light leaves the object.
10. Use Snell’s Law to calculate the index of refraction of your material. You
will make this calculation for each set of angles.
11. Average the two values together. This is the material’s index of refraction.
12. Use the definition of the index of refraction to calculate the speed of light
through the material.
13. Show all calculations on your ray diagram.
1
CMSE Phys
II. Circular Water Dish
1. Place the circular water dish on the center of your paper. Trace around it.
Carefully fill to near the top with water.
2. Place two pins on one side of the dish, one snugly against the side slightly off
the center of the dish and the other directly in line with it. (Pins A and B in
diagram)
3. Look through the dish until these two pins line up in your eyesight. Place
another pin on the other side of the dish snugly against the side so that all
three pins that are lined up in sight. (Pin C in diagram)
4. Place a fourth pin (Pin D) behind the dish in line with the other three. You
should see all four pins lined up when you look through the dish.
5. Remove the water dish and pins.
6. Connect the pin holes to show the path of light traveling through the dish.
7. With your ruler, carefully draw a dotted line “normal” to the circular surface
where the light ray enters the dish. Draw another one where the light ray
leaves the dish. The normal will be a line through the center of the circular
dish.
8. Measure the angles of incidence and refraction where the light enters and
where the light leaves the dish.
9. Use Snell’s Law to calculate the index of refraction of the water. You will
make this calculation for each set of angles.
10. Average the two values together. This is the water’s index of refraction.
11. Use the definition of the index of refraction to calculate the speed of light
through the water.
12. Show all calculations on your ray diagram.
2
CMSE Phys
Lens Ray Diagrams
Calculate the image distance and size for each case. Enter these values in the data
table.
Using unlined paper in a landscape orientation, draw ray diagrams in order to find
the image of each 2.0 cm object. Draw a double convex lens for the converging
lenses and a double concave lens for the diverging. Label the focus F on each side
of the lens. Draw three rays (through or toward focus and parallel, parallel and
through or away from focus, and through optical center) if possible. Measure the
image size and distance. Record these values in the data table and compare with
the calculated.
On your diagrams, classify each image as 1) REAL or VIRTUAL, 2) UPRIGHT or
INVERTED, and 3) REDUCED, ENLARGED, or SAME SIZE.
Lens
Converging
Converging
Converging
Converging
Converging
Diverging
Diverging
Diverging
Diverging
Diverging
Object
Distance
18.0 cm
12.0 cm
9.0 cm
6.0 cm
3.0 cm
15.0 cm
10.0 cm
7.0 cm
4.0 cm
1.0 cm
Object
size
2.0 cm
2.0 cm
2.0 cm
2.0 cm
2.0 cm
2.0 cm
2.0 cm
2.0 cm
2.0 cm
2.0 cm
Focal
Length
6.0 cm
6.0 cm
6.0 cm
6.0 cm
6.0 cm
-5.0 cm
-5.0 cm
-5.0 cm
-5.0 cm
-5.0 cm
Calculated
di
si
Measured
di
si
***Notice that the focal length of a diverging lens is negative.***
CMSE Phys
Images from Converging Lenses
Learning Tasks:
Complete and hand in one copy of the “PreLab Predictions” before picking up your equipment.
Resources:
converging lenses, candles, textbook, meter stick,
computer simulation at http://www.schulphysik.de/suren/ CurvSurf/CurvSurf.html
Part I: Blocking the Front of the Lens
Use the available resources (candles, lenses, computer simulation, textbook, peer counsel) to
answer the following questions:
a) What happens to the image formed by a converging lens when the top half of the
front side of the lens is covered?
b) What happens to the image formed by a converging lens when the bottom half of the
front side of the lens is covered?
c) What happens to the image formed by a converging lens when a central portion of
front side of the the lens is covered?
d) What happens to the image formed by a converging lens as more and more of the
front side of the lens is covered?
1
CMSE Phys
Part II: Blocking the Back of the Lens
Use the available resources (candles, lenses, computer simulation, textbook, peer counsel) to
answer the following questions:
a) What happens to the image formed by a converging lens when the top half of the
back side of the lens is covered?
b) What happens to the image formed by a converging lens when the bottom half of the
back side of the lens is covered?
c) What happens to the image formed by a converging lens when a central portion of
back side of the the lens is covered?
d) What happens to the image formed by a converging lens as more and more of the
back side of the lens is covered?
Part III: Blocking the Object
Use the available resources (candles, lenses, computer simulation, textbook, peer counsel) to
answer the following questions:
a) What happens to the image formed by a converging lens when the top half of the
object is covered?
b) What happens to the image formed by a converging lens when the bottom half of the
object is covered?
c) What happens to the image formed by a converging lens when a central portion of
the object is covered?
d) What happens to the image formed by a converging lens as more and more of the
object is covered?
Develop an explanation of your answers using the behavior of light through lenses as
justification.
Write and hand in a complete and organized explanation that includes diagrams to justify
your responses.
2
CMSE Phys
PRELAB: Images from Converging Lenses
Draw a sketch of what you think the image on the screen would look like when various
portions of the lens/object are covered. Sketch in some rays traveling from the object to
the screen that would form such an image.
Part I: Blocking the Front of the Lens
a) What happens to the image formed by a converging lens when the top half of the
front side of the lens is covered?
b) What happens to the image formed by a converging lens when the bottom half of the
front side of the lens is covered?
c) What happens to the image formed by a converging lens when a central portion of
front side of the the lens is covered?
Part II: Blocking the Back of the Lens
a) What happens to the image formed by a converging lens when the top half of the
back side of the lens is covered?
3
CMSE Phys
b) What happens to the image formed by a converging lens when the bottom half of the
back side of the lens is covered?
c) What happens to the image formed by a converging lens when a central portion of
back side of the the lens is covered?
Part III: Blocking the Object
a) What happens to the image formed by a converging lens when the top half of the
object is covered?
b) What happens to the image formed by a converging lens when the bottom half of the
object is covered?
c) What happens to the image formed by a converging lens when a central portion of
the object is covered?
.
4
CMSE Phys
FUN WITH LIGHT AND COLO R
Many students are taught in art classes that the 3 PRIMARY COLORS are:
_______________, _______________, and _______________.
From our own experiences with paint and/or crayons, we know that mixing different amounts
of these 3 colors will produce other colors. For example,
RED and YELLOW liquids combine to form _______________ liquid,
RED and BLU E liquids combine to form _______________ liquid,
BLU E and YELLO W liquids combine to form _______________ liquid, and
BLU E, YELLO W, and RED liquids combine to form _______________ liquid.
Many do not know that mixing colors of LIGHT is quite different from mixing colors of
PAINT.
To begin with, the 3 PRIMARY COLORS OF LIGHT are not red, blue, and yellow, but rather
RED, BLU E, and GREEN . These 3 colors, or FREQUENCIES, of light combine in different
ways than do colors of paint. Believe it or not,
RED and G REEN light combine to form _______________ light,
RED and BLU E light combine to form _______________ light,
BLU E and GREEN light combine to form _______________ light, and
BLU E, GREEN , and RED light combine to form _______________ light.
Isaac Newton was perhaps the first person known to separate WHITE LIGHT into its
component colors of ________, ________, ________, ________, ________, and
________. To do this, he used two PRISMS - one to separate light into its component
colors, and the other to recombine them into white light. This method of separating light
into its component colors uses the property of light known as REFRACTION.
Another way to separate any light into its component colors is through properties of light
known as DIFFRACTION and INTERFERENCE. A simple SPECTROSCOPE allows light to
pass through a diffraction grating in such a way that the colors making up that light become
known through these two processes.
Learn more about mixing light and color by viewing these simulations on the World Wide Web:
http://www.physicslessons.com/exp16b.htm
http://www.physicslessons.com/exp18b.htm
http://www.physicslessons.com/exp19b.htm
1
CMSE Phys
MAKE YOUR OWN S PE CT ROS COPE
Materials:
hollow tube (paper towel roll, bamboo, toilet paper roll, etc…) , old compact disk, scissors,
tape, card stock, exacto knife or razor blade, marker
Procedure:
1. Place one end of your tube on the card stock and trace around the circle. (You may
want to cut “flaps” around the disk for connection purposes.)
2. Use scissors to carefully cut this circle out of the card stock.
3. NOW USE THE RAZOR BLADE OR EXACTO KNIFE TO CAREFULLY CUT A
NARROW VERTICAL SLIT IN THE CARD STOCK CIRCLE. This slit should be
about 1-2 centimeters long and 1-2 millimeters wide.
4. Place this slit circle on one end of the tube and tape it into place.
5. Now place the other end of the tube on the compact disk and trace around the circle
with the marker.
6. Use scissors to carefully cut this plastic circle out of the compact disk.
7. Use tape to pull the metallic covering off the top of the compact disk until it becomes
totally transparent.
8. Place the compact disk circle on the other end of the tube and hold it into place. Do
not tape it at this time.
9. While holding the tube so that the slit is vertically oriented, look through the compact
disk end of the tube at a distant light.
10. Keep the slit circle vertical and rotate the compact disk circle until you see vertical
color bands on both the right and left sides of the vertical slit.
11. Once you have it properly oriented, tape the compact disk end in place.
12. Look at various light sources and determine the colors of light comprising each source
of light. Most incandescent and fluorescent bulbs contain all colors of the spectrum,
but other gas-filled tubes contain only colors that are characteristic of the gases.
Label each color of light seen when looking at a “white” light source.
2
CMSE Phys
Electrical and Magnetic Properties
Use the power supply, switch, wires, and light bulb to create a complete circuit that lights
the bulb. Then check the electrical conductivity and magnetic attractiveness of each of
your supplied materials.
Object
Conducts Electricity?
Yes
No
Attracted to Magnet?
Yes
No
On the back of this page, write some generalizations about:
1. conductivity and type of object
2. magnetic attraction and type of object
3. relationship, if any, between magnetic attraction and electrical conductivity
CMSE Phys
Ohm’s Law
Objectives:
•
•
•
•
•
determine the conductivity of various materials
set up a simple resistor circuit
measure current through a resistor using an ammeter
measure potential difference across a resistor using a voltmeter
determine resistance and verify Ohm’s Law (i.e., R = V/I is constant)
Materials:
•
D-cells and cell holders, multi-meters, wire, resistors, switch
Procedure:
•
•
•
•
•
•
•
•
•
•
Build a circuit to test the conductivity of materials in the bag.
Test these materials and complete the chart.
Draw both pictorial and schematic diagrams illustrating a circuit that includes the
Ohm’s Law materials.
Connect materials as shown in the diagrams.
Record data from the multi-meters (used as a voltmeter and an ammeter) for six
trials (using 1 - 6 cells in series) for each resistor.
For each trial, divide “Potential Difference” by “Current” to obtain the “Resistance”
for that trial (R = V/I). Average the trials for each resistor to obtain the “data
table value” of resistance.
Make a graph of “Potential Difference vs. Current” for each resistor. Include the
origin (0,0) as a data point.
Find the slope of the line that best fits your points. Enter this value as the “graph
value” for the unknown resistance.
Use the resistor color codes to determine the accepted resistance of each resistor.
Compare your experimental value with the accepted value in a conclusion paragraph.
Be sure to list sources of error in this activity.
Pictorial Diagram
Schematic Diagram
1
CMSE Phys
Resistor I
Color Bands -
trial
potential diff (V)
current (Amps)
resistance (Ω )
Average Resistance (Ω ) =
Resistor II
II
Color Bands -
trial
potential diff (V)
current (Amps)
resistance (Ω )
Average Resistance (Ω ) =
Resistor III
I
0
0
-
-
I
0
0
-
III
I
0
0
-
IV
II
II
IV
III
V
VI
VII
V
VI
VII
VI
VII
-
III
Color Bands -
trial
potential diff (V)
current (Amps)
resistance (Ω )
Average Resistance (Ω ) =
-
IV
V
Analysis of Results
resistor
color code
accepted
value, Ω
data table
value, Ω
% error
graph
value, Ω
% error
Conclusion:
2
CMSE Phys
Light Bul bs in Seri es, P arall el, a nd C ombi nati on
Each group must hand in their pre-lab predictions before obtaining the materials for this investigation.
Learning Tasks:
1. Use the available resources (bulbs and circuit items, web-based circuit simulation, text, peer counsel) to determine what happens to
the brightness of identical light bulbs in a dc circuit as more and more bulbs are a) added in series and b) added in parallel.
2. Develop a thorough explanation of why this occurs.
3. Use these same resources to develop an explanation of how one can determine the relative brightness of multiple bulbs when they
are connected in combination circuits.
4. Hand in a complete explanation of your findings, containing multiple examples comparing the brightness of the bulbs in each type
of circuit (series, parallel, and combination). Your explanation should include a method of how one may look at a schematic diagram
of a combination circuit and be able to a) list the bulbs in order of increasing or decreasing brightness and b) tell which bulbs
would be equally bright. Illustrate your method with two or more examples containing at least six bulbs in each of varying
brightness.
Resources:
bulbs, wire, D cells, cell holders,
multi- meters, textbook, peer counsel,
computer simulation of a circuit found at
http://www.physicslessons.com/exp22b.htm
1
CMSE Phys
Light Bul bs in Seri es, P arall el, a nd C ombi nati on: Pre- Lab P redic tions
2
CMSE Physics
Electrical Energy Costs
The kilowatt-hour (kWh) is the basic unit of electrical energy used in determining one’s electrical utility
costs. Since POWER = WORK /TIME (P = W/t), the kWh is actually a unit of WORK (W = P x T), or
ENERGY, and is not a unit of power, as it is commonly believed and referred to. Therefore, one kWh
(“kilo-Watt hour”) is equal to the total energy “consumed” (or “transferred”) by an electrical device with a
power rating of one kilowatt during each hour of use.
The electrical utility company will typically charge a home a set monthly rate for service plus an additional
cost for each kWh used during the month. These rates vary by location, but generally fall between 5 and
10 cents ($0.05 - $0.10) per kWh. To find the total cost for using an electrical appliance in your home for
one month, first find the number of kWh of energy used by multiplying its power (in kilowatts) by the total
amount of time (in hours) used during the month. You may have to do some unit conversions to obtain
this total. Then multiply this value by the cost per kWh to find the total cost.
Procedure:
I. Find the total monthly cost for using these devices, given the estimated times of usage. Assume a 30
day month and $0.075 per kWh.
Appliance
night light
porch light
radio
microwave
television
central air
clock
hair dryer
iron
ceiling fan
Power
5W
60 W
20 W
750 W
88 W
8200 W
10 W
1800 W
1200 W
12 W
Usage
9 hr/night
12 hr/night
4 hr/day
30 min/day
6 hr/day
15 min/hr
all day
5 min/day
4 hr/week
8 hr/day
Total Time
Total kWh
Cost
II. Make a chart similar to the one above and find out how much your family pays to use electrical
devices each month by finding 15 (fifteen) examples in your own home. Be sure to make a realistic
estimate of the actual amounts of time they are in use. Your 15 examples may include a maximum of
5 light fixtures or bulbs.
Believe it or not, several students in the past have copied others work or just made up something to turn
in and have missed the benefit of this assignment. Therefore, you must have this paper signed by a
parent or guardian before handing it in to verify your own original work.
“I verify that my child completed this assignment by finding actual examples in our home and doing
his/her unique work.”
Signature: _________________________________________
Date: ______________
CMSE Phys
Electromagnet Strength
Determine how the potential difference (voltage) applied to an electromagnet (with
a fixed number of turns) affects its strength by comparing the applied potential
difference to the electromagnet’s attraction to a force scale.
# Turns of Wire
# “D” Cells
Electric Potential
Difference, Volts
Strength, N
1
2
3
4
5
6
Make a graph of Electromagnet Strength vs. Potential Difference. Include the
origin as one of your data points.
What does the shape of this graph indicate about the relationship between an
electromagnet’s strength and its applied potential difference?
Now use a fixed potential difference and vary the number of turns of wire to see
how the number of turns of wire affects the strength of the elec tromagnet.
# “D” Cells
Electric Potential
Difference, Volts
# Turns of Wire
Strength, N
4
4
4
4
4
4
Make a graph of Electromagnet Strength vs. # Turns of Wire. Include the
origin as one of your data points.
What does the shape of this graph indicate about the relationship between an
electromagnet’s strength and its number of turns of wire?
What would you need to do to make a really strong electromagnet?
CMSE Phys
FUN W ITH E LE CT RI CIT Y AND M AGNET ISM
When a complete circuit is connected to a power supply, electric current, made up of
extremely tiny particles (or waves, but that is another very long story) called electrons, flows
through the wire and other circuit elements and transfer electric potential energy. This
energy may be used to produce light, generate heat, and/or cause motion that we use in many
products every day.
Connect the circuit, throw the switch, and make the light bulb glow.
Over 100 years ago, scientists discovered that when electric current flows through a wire, a
magnetic field is produced around the wire.
Open the switch, place a compass under the wire so that the wire lines up
with the compass needle, and then close the switch. What do you notice?
The deflection of the compass needle indicates the presence of a magnetic field around the
current bearing wire. This knowledge soon led to practical applications of this phenomenon,
including the construction of strong electromagnets that can be turned on and of at will,
motors for converting electric energy into mechanical energy, and generators for converting
mechanical energy into electric energy.
A simple electric motor can be constructed in a very short time using common and inexpensive
materials. To do this, a current-bearing loop of wire is constructed in a manner that causes
the magnetic field from a nearby ceramic magnet to interact with the magnetic field
surrounding the current-bearing wire loop and cause the loop of wire to spin.
M AKE YOUR OWN DC EL EC TRI C MO TOR
Materials:
dry cell, small disk magnet, rubber band, 2 large paperclips,
about 2 feet thin wire, nail, test tube or thick marker, scissors
Procedure:
1. Take the 2 foot piece of thin wire and
wrap it around the test tube (or thick
marker). The number of wraps depends
on the gauge (“thinkness”) of the wire.
2.
“Tie” the ends of the wire through the
loops so that the loop of wire will remain
in place when you let go.
1
CMSE Phys
3. Bend the paper clips in order to form loops on their ends,
which will be used for holding the wire loop.
4.
Secure these to the dry cell with the rubber band.
5. Place the magnet on the dry cell
and place the wire loop in its
holders. Observe what happens.
6. Disappointed that nothing happened? The reason is that the wire is insulated with
paint, which must be scraped off. This is the trickiest part. Whether or not the ends
of the wire loop are scraped correctly will determine the
success of your motor.
7. Hold the wire loop vertically between your thumb and index
finger of one hand near the edge of the table (desk) so that
the wire end lies on the table.
8. Use the other hand and the scissors to scrape the insulation off the top half of the
wire.
9. Turn the wire loop around and scrape the top half of the other end.
10. Place the wire loop into its holders and move the loop so that it lies just above the
magnet. The motor should now begin spinning. If not, you may need to give it a little
push to get it going.
Other instructions and pictures of electric motors made
in similar ways may be found on the World Wide Web at:
http://fly.hiwaay.net/~palmer/motor.html
http://www.exploratorium.edu/snacks/stripped_down_motor.html
http://www.scitoys.com/scitoys/scitoys/electro/electro.html#motor
2
CMSE Phys
Simulated Radioactive Decay - Dice
Instructions:
1. Complete the “Theoretical Decay” table entries by assuming
that exactly 1/6 of all nuclei initially present decay each time
period. Do this by taking 1/6 of the “initial number present”
and round to the nearest whole number. Enter this number
as the “number decayed.”
2. Subtract this value from the “initial number present” and record as the “number
remaining.”
3. Repeat this process until the chart is complete or fewer than ten nuclei remain
undecayed.
4. Make a graph of “Number of Radioactive Nuclei Present vs Time – Theoretical.” Draw
a smooth curve through your data points.
Now repeat this process using the dice to represent the unstable nuclei:
5. Begin with 300 dice. Toss the dice and remove each one showing
the number ____________. The number you remove will be the
“number decayed.”
6. Subtract the “number decayed” from the “initial number present”
to obtain the “number remaining.”
7. Toss the remaining dice and again remove all those that “decay.”
8. Repeat this process until the chart is complete or fewer than ten dice remain.
9. Make a graph of “Number of Radioactive Nuclei Present vs Time – Experimental.”
Draw a smooth curve through your data points.
Discussion:
a. Compare your “Theoretical Decay” chart and graph with the “Experimental Decay”
chart and graph.
b. Use the graph to estimate the amount of time necessary for your experimental
number to go from 300 to 150 _____, 250 to 125 _____, 200 to 100 _____, 150 to 75
_____, and 100 to 50 _____.
c. Based on your answers above, what is the approximate half-life of your “radioactive”
sample?
Extension:
Repeat this decay simulation using more than one digit to represent a decayed nucleus and
compare with the previous results.
1
CMSE Phys
Data Table - Dice
Elapsed
Time
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
Dice: Theoretical Decay
Initial
Number
Number
Number
Decayed
Remaining
Present
300
Dice: Experimental Decay
Initial
Number
Number
Number
Decayed
Remaining
Present
300
2
CMSE Phys
Simulated Radioactive Decay - Random Numbers
Instructions:
1. Complete the “Theoretical Decay” table entries by assuming that exactly 1/10 of all
nuclei initially present decay each time period. Do this by taking 1/10 of the “initial
number present” and round to the nearest whole number. Enter this number as the
“number decayed.”
2. Subtract this value from the “initial number present” and record as the “number
remaining.”
3. Repeat this process until the chart is complete or fewer than ten nuclei remain
undecayed.
4. Make a graph of “Number of Radioactive Nuclei Present vs Time – Theoretical.” Draw
a smooth curve through your data points.
Now repeat this process using the dice to represent the unstable nuclei:
5. Begin with 500 random digits. Choose the digit _____ and mark through each one of
these. The number you mark out will be the “number decayed.”
6. Subtract the “number decayed” from the “initial number present” to obtain the “number
remaining.”
7. Block out the remaining number of digits and again mark through all those that “decay.”
8. Repeat this process until the chart is complete or fewer than ten digits remain.
9. Make a graph of “Number of Radioactive Nuclei Present vs Time – Experimental.”
Draw a smooth curve through your data points.
Discussion:
a. Compare your “Theoretical Decay” chart and graph with the “Experimental Decay”
chart and graph.
b. Use the graph to estimate the amount of time necessary for your experimental
number to go from 500 to 250 _____, 400 to 200 _____, 300 to 150 _____, 200 to
100 _____, and 100 to 50 _____.
c. Based on your answers above, what is the approximate half-life of your “radioactive”
sample?
Extension:
Repeat this decay simulation using more than one digit to represent a decayed nucleus and
compare with the previous results.
3
CMSE Phys
Data Table - Random Numbers
Random Numbers:
Theoretical Decay
Elapsed
Time
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
Initial
Number
Present
500
Number
Decayed
Number
Remaining
Random Numbers:
Experimental Decay
Initial
Number
Present
500
Number
Decayed
Number
Remaining
4
CMSE Phys
Random Digits Chart
http://www.rand.org/publications/classics/randomdigits/randomdata.html
00000
00001
00002
00003
00004
00005
00006
00007
00008
00009
00010
00011
00012
00013
00014
00015
00016
00017
00018
00019
00020
00021
00022
00023
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37542
08422
99019
12807
66065
31060
85269
63573
73796
98520
11805
83452
88685
99594
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91499
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63606
61196
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94557
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46058
32179
69234
19565
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94864
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74029
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48324
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90324
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58044
5
CMSE Phys
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51926
28834
73852
10123
34313
71602
56271
21815
64638
85794
96207
59175
05128
13499
64421
88835
90822
56196
49632
07477
36699
62126
35700
11883
91342
04285
31649
86283
79246
45134
58838
52623
07759
27493
11161
66083
81997
64464
12272
27398
58873
07893
90290
90212
17646
82774
29773
73156
91345
12830
64721
34137
70091
91622
65861
92937
10086
39250
85902
74296
44156
20695
09719
06319
80814
54486
97022
80091
24041
44606
53728
98408
04754
09528
37821
01392
42096
68258
86686
26529
73859
07992
51777
70939
78576
24653
91870
27124
95375
20714
04618
32604
28466
55781
48949
51908
74287
07082
42836
74819
58303
73515
61222
85496
45875
74219
47324
75237
49139
08789
23821
05533
77433
53075
43800
23768
17719
82067
08337
17985
28825
12843
83824
63011
88325
17974
63281
69572
76463
26760
49364
12369
97377
85130
45819
84609
76150
67018
05871
53295
97553
60475
68795
76514
72306
13980
75251
85046
09191
78142
29822
90400
60561
57560
21069
64049
62605
62047
06441
88156
99538
52139
53783
71839
09351
06156
04207
63400
65676
48911
35793
82590
52692
98901
80851
15077
02023
13798
34222
83637
73331
18601
27585
32552
52979
58232
68476
41361
93823
07706
31223
94119
77762
83483
94541
72893
65344
31853
08007
43860
93174
71148
62327
81604
85644
65584
40030
15501
03856
64691
04713
61212
92301
06410
31024
04111
95954
05462
96299
97341
28976
09815
54130
14974
43667
90712
08816
16435
26655
41326
96240
03742
51972
54846
65130
88618
64659
82760
43178
17813
08420
01840
20791
47055
37408
55507
67415
38452
45449
72834
93972
43643
18423
18880
47277
49698
37438
29578
54552
19202
66994
06455
50498
19362
73167
08408
49953
69200
90836
30358
66252
93146
55160
40344
70883
26769
47449
91529
90802
44344
43642
83873
37867
54759
04860
19161
6
CMSE Phys
7
CMSE Phys
8