AP Physics 1 Question 385: Answer and Explanation
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3. A box with a mass of 5 kg is sliding across a table at a speed of 2 m/s. The coefficient of kinetic friction between the book and table is μ = 0.25. What is the minimum force that has to be applied on the box to maintain this speed?
- A. 0 N
- B. 10 N
- C. 12.5 N
- D. 25 N
Correct Answer: C
The minimum force exerted to maintain the speed of 2 m/s will result in no acceleration. Thus, the force required will result in Fnet = 0. The friction force acting against the motion is
Thus, the force required to maintain the speed is 12.5 N, just enough to counteract the friction force.