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Exercise 4: Understanding friction as a function of applied force

Exercise 4.1 (2 marks)

Compare your coefficient of static friction (µs) and kinetic friction (µk), which one is bigger? Does this make sense? Explain why or why not in 2-3 sentences.

Exercise 4.2 (1 mark)

The graph below shows the force of friction as a function of applied force for a shoe on a ramp. Consider the scenario where the applied force increases steadily from zero, moving left to right along the x-axis. Describe what is happening in region 1 and region 2, which are separated by the dotted line. Pick the correct option(s) directly on Crowdmark.

 

Force of friction as a function of the applied force. In region one the force of friction is equal to the applied force. In region 2 the force of friction is constant after dropping down from a maximum value.

Exercise 4.3 (1 mark)

Now imagine that you perform the same experiment (where the applied force is increasing, moving from left to right along the plot) with a second shoe. Let ‘Shoe B’ have the same static and kinetic friction coefficients but have half the mass as ‘Shoe A’. In the graph below, ‘Shoe A’ is represented by the solid pink curve. Which curve represents the force of friction as a function of applied force for ‘Shoe B’? Pick the correct option(s) directly on Crowdmark.
A graph of the force of friction as a function of the applied force with 5 different curves. A solid pink line represents Shoe A. This curve constantly increases until sharply falling off and dipping at its maximum frictional force. A solid red line shows a similar curve, but it has half the maximum friction and has a more shallow dip. A dashed green line shows a curve that increases steeply with little applied force until shallowly dipping. A solid blue line show a curve constantly increasing until sharply falling off and dipping. The solid blue line is the same shape as the solid red line, but with a quarter of the maximum friction. Finally, the black dashed line increases slowly and then dips shallowly.

Before you continue!

Before continuing, be sure you have completed (4.1), (4.2), and (4.3), which will be graded and submitted through Crowdmark.

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Physics 1A03 - Laboratory Experiments Copyright © by Physics 1A03 Team is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License, except where otherwise noted.

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