Physics
Friction Problems
1. A 50kg box is resting on a smooth surface. In physics, smooth surfaces are imaginary surfaces that have no friction. A person pulls on the block with 5N of force. Find the acceleration of the block.
2. The 50kg block from problem 1 is moved to a rough surface. In physics, rough surfaces are real surfaces that have friction. The μs for the surface is .4 and the μk is .3. Calculate how much force is needed to start the block into motion.
3. How much force is needed to keep the 50kg block moving against the force of friction?
4. If a 200N force is applied to the block while it is moving, what will the acceleration be?
5. (Bonus) What will the force of friction be if a 500N force is applied at 45 degrees upwards of horizontal?
6. What will the acceleration be in problem 5?
7. A block rests on an inclined plane. μk is .35 between the surface and the block. What is the acceleration of the block if the plane is inclined at an angle of 25 degrees? Since we are more comfortable doing the problems if the block has a mass, assume the block has a mass of 1kg.
8. If we have a smooth 30 degree inclined plane with a 2kg block what force is needed to keep the block from accelerating down the plane?
9. Redo problem 8 where the plane is rough and μs is .1.
10. What force is needed to accelerate a 2kg block up a 30 degree inclined plane at 2m/s2 if the plane has μk .1?
11. A 50kg person skis down a 20 degree slope. The μk between the skis and the snow is .1. Find the acceleration down the slope.
12. Find the velocity of the skier in 11 after 5s.
13. Find the displacement of the skier in 12.
14. If the skier in 13 skis on to a flat surface with μk of .15. Find how much time and displacement it takes for them to stop.
15. A truck with mass 20,000kg is travelling at 40m/s when its brakes fail. It goes on to the runaway truck ramp which has a μk of .25. Find out how much time and displacement it takes the truck to stop.