Physics Worksheet (Friction)

1. A 25 kg block is initially at rest on a rough, horizontal surface. A horizontal force of 75 N is required to set the block in motion, and a 60 N force is required to keep it in motion at a constant speed once it is moving. What are the coefficients of static and kinetic friction?

2. The coefficient of static friction between a 10 kg object and the floor is 0.50. What is the maximum force that can be applied on the object before it starts moving?

3. A 100 kg object moving at 20 m/s comes to a stop over a distance of 40 m. What is the coefficient of kinetic friction between the object and the ground?

4. A hockey puck is hit on a frozen lake and starts moving with a velocity of 12.0 m/s. 5.0 seconds later, the velocity of the puck is 6.0 m/s. What is the coefficient of friction between the puck and the ice?

5. A 100 kg object is at rest on a horizontal surface. The coefficient of static friction between the object and the surface is 0.60, while the coefficient of kinetic friction between the object and the surface is 0.45.

a) If a force of 400 N for 5.0 seconds, what will be the force of friction acting on the object?

b) If a force of 650 N is applied for 5.0 seconds, what will be the force of friction acting on the object?

c) How much applied force is required for the object to start moving?

6. Provide one situation where you would want to have a low coefficient of static friction and one situation where you would want to have a high coefficient of static friction.

7. Provide one situation where you would want to have a low coefficient of kinetic friction and one situation where you would want to have a high coefficient of kinetic friction.