Name ______________________________ Class___________________Date__________________
Application Lab
DATASHEET A
Static, Sliding, and Rolling Friction
Current car brakes make use of static friction. As an engineer in the research and
development department of a car manufacturing company, you have been asked to
find out if a different approach to brakes might work better. To do so, you will
investigate the circumstances under which friction is maximized.
WHAT YOU’LL DO
Predict which type of friction force—static, sliding, or rolling—will be greatest
and which will be smallest.
Measure the static, sliding, and rolling friction when pulling a textbook across a
table.
Apply your results by describing how friction affects objects being pulled across a
surface.
WHAT YOU’LL NEED
•
•
•
•
•
rods, wooden (or metal) (4)
scissors
spring scale
string
textbook
SAFETY
PROCEDURE
Preparing for Your Experiment
1. Remember:
• Static friction is friction between a surface and an object that is not moving.
• Sliding friction is friction between a surface and an object sliding past the
surface.
• Rolling friction is friction between a surface and a round object rolling over
the surface.
Which type of friction do you think is the largest force?
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Which type of friction do you think is the smallest force?
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Original content Copyright © by Holt, Rinehart and Winston. Additions and changes to the original content are the responsibility of the instructor.
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Motion
Name ______________________________ Class___________________Date__________________
Static, Sliding, and Rolling Friction continued
2. Form a hypothesis.
• Write a sentence about the largest friction force. Why is it the largest force?
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• Write a sentence about the smallest friction force. Why is it the smallest
force?
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• Write a sentence about the friction force that is not the largest or the
smallest.
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3. Use the data table below to record your results.
CAUTION: Secure loose clothing, and remove dangling jewelry. Do not wear
open-toed shoes or sandals in the lab.
DATA TABLE: FRICTION MEASUREMENTS
Static friction (N)
Sliding friction (N)
Rolling friction (N)
Trial 1
Trial 2
Trial 3
Total of the 3 trials
Average of the 3 trials
Collecting Data and Testing the Hypothesis
4. Look at the picture. Prepare the textbook.
• Cut a piece of string.
• Tie it in a loop that fits inside a textbook.
• Hook the string to the spring scale as shown in the picture.
5. Measure the static friction between the book and the table.
• Practice pulling the spring scale very slowly.
• Gradually increase the force with which you pull on the spring scale until the
book starts to slide across the table.
• Pull very gently. If you pull too hard, the book will start lurching and you
will not get accurate results.
Original content Copyright © by Holt, Rinehart and Winston. Additions and changes to the original content are the responsibility of the instructor.
Holt Science Spectrum
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Motion
Name ______________________________ Class___________________Date__________________
Static, Sliding, and Rolling Friction continued
6. Practice pulling the spring scale several times until you can pull back
smoothly.
• When you can pull the book smoothly, watch the spring scale.
• What is the largest force that appears on the spring scale before the book
starts to move?
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• Write down the force in your data table in the “Static friction (N)” column as
Trial 1.
7. Repeat step 6 two more times, and record the results in your data table as
Trials 2 and 3.
8. Measure the sliding friction between the book and the table.
• Start pulling the book as you did in step 5.
• When the book starts to slide, continue applying just enough force to keep
the book sliding at a slow, constant speed.
• Practice pulling the book several times.
• When you can pull the book smoothly, watch the spring scale.
• What is the largest force that appears on the spring scale before the book
starts to move?
_______________________________________________________________
• Write down the force in your data table in the “Sliding friction (N)” column
as Trial 1.
9. Repeat step 8 two times, and record the results as Trials 2 and 3 in your data
table.
Original content Copyright © by Holt, Rinehart and Winston. Additions and changes to the original content are the responsibility of the instructor.
Holt Science Spectrum
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Motion
Name ______________________________ Class___________________Date__________________
Static, Sliding, and Rolling Friction continued
10. Measure the rolling friction between the book and the table.
• Place two or three rods under the textbook to act as rollers.
• Make sure the rods are evenly spaced.
• Place another rod in front of the book so that the book will roll onto it.
• Pull the spring scale slowly so that the book rolls across the rods at a slow,
constant speed.
• Practice this several times. Make sure the rods are evenly spaced each time.
• When you can pull the book smoothly, watch the spring scale.
• What is the largest force that appears on the spring scale before the book
starts to move?
_______________________________________________________________
• Write down the force in your data table in the “Rolling friction (N)” column
as Trial 1.
12. Repeat step 10 two times, and record the results as Trials 2 and 3 in your data
table.
ANALYSIS
1. Organizing Data Look at the columns in your data table.
• Add the results of the three trials for each type of friction
• Put your results in the row “Total of the 3 trials.”
• Use the space below to add the numbers.
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• Divide each of the totals by 3.
• Put your results in the row “Average of the 3 trials.”
• Use the space below to divide the numbers.
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
Original content Copyright © by Holt, Rinehart and Winston. Additions and changes to the original content are the responsibility of the instructor.
Holt Science Spectrum
44
Motion
Name ______________________________ Class___________________Date__________________
Static, Sliding, and Rolling Friction continued
2. Analyzing Data Look at the row “Average of the 3 trials” in the data table.
• Which of the three types of friction was the largest force, on average?
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3. Analyzing Data Look at the row “Average of the 3 trials” in the data table.
• Which of the three types of friction was the smallest force, on average?
_______________________________________________________________
COMMUNICATING YOUR RESULTS
4. Drawing Conclusions Look at the sentences you wrote for your hypothesis in
step 2.
• Did your answers to Analysis questions 2 and 3 agree with the sentences in
your hypothesis?
_______________________________________________________________
• If your answers were not the same as your hypothesis, how were your
answers different?
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_______________________________________________________________
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5. Evaluating Methods In each trial, you measured the force you exerted on the
spring scale. This force was, in turn, exerted on the book.
• Why do you think that this force was equal to the force of friction in each
case? (Hint: Think about how the forces are balanced when the book is
moving.)
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
Original content Copyright © by Holt, Rinehart and Winston. Additions and changes to the original content are the responsibility of the instructor.
Holt Science Spectrum
45
Motion
Name ______________________________ Class___________________Date__________________
Static, Sliding, and Rolling Friction continued
APPLICATION
If the car manufacturer that you work for wants to develop a new braking system,
should it be based on a kind of friction different from that used in braking systems
now?
• What kind of friction should the car manufacturer use in the braking system?
(Remember that braking systems now use static friction.)
Original content Copyright © by Holt, Rinehart and Winston. Additions and changes to the original content are the responsibility of the instructor.
Holt Science Spectrum
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Motion