1. When investigating the 'relationship between sliding friction and pressure', the variable that must be kept constant is:
- A. Roughness of the contact surface
- B. Normal force on the object
- C. Size of the contact area
- D. Speed of the object
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Sliding Friction - Quiz
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When investigating the 'relationship between sliding friction and pressure', the variable that must be kept constant is:
Sliding Friction - Quiz - Quiz Questions
Test your understanding of the factors affecting friction using the control variable method through the following exercises.
2. In the experiment, the wooden block must be pulled 'horizontally at a constant speed'. The purpose of this is:
- A. To make friction disappear
- B. To make the pulling force equal to the friction force
- C. To reduce wear
- D. To increase the difficulty of the experiment
3. Changing the wooden block from flat to side, it is found that the spring dynamometer reading remains unchanged. This shows:
- A. Sliding friction is related to pressure
- B. Sliding friction is related to roughness
- C. Sliding friction is independent of contact area
- D. There is no friction when placed on the side
4. True/False: Pushing a box on ice is easier than on a concrete floor, indicating that the coefficient of kinetic friction $\mu$ of the ice surface is smaller.
- True
- False
5. A student found during the experiment that the speed of pulling the wooden block became a little faster, but it still maintained a constant speed. At this time, the friction force:
- A. Becomes larger
- B. Becomes smaller
- C. Remains unchanged
- D. Becomes zero
6. If a wooden block weighs $2N$, and the dynamometer reading is $0.5N$ when pulling at a constant speed. What is the sliding friction coefficient $\mu$ of the board against the block? (Formula $f = \mu N$)
- A. 0.25
- B. 4.0
- C. 0.5
- D. 2.5
7. The main principle of the Anti-lock Braking System (ABS) of a car is most related to which of the following factors?
- A. Reduce car mass
- B. Use the fact that maximum static friction is usually greater than sliding friction
- C. Increase tire pressure
- D. Reduce brake pad area
8. Design an experiment: If you want to verify 'sliding friction is independent of contact area', how should you operate?
- A. Place the rectangular wooden block on its side and flat, keeping pressure and roughness unchanged, and pull at a constant speed.
- B. Cut the wooden block in half and pull at a constant speed.
- C. Put more towels under the wooden block.
- D. Increase the speed of pulling the wooden block.