Don't even think of memorizing anything in this table!
m (coefficient of friction) oak on oak, dry
steel on steel, dry
steel on steel, greasy
steel on ice
rubber on asphalt, dry
rubber on asphalt, wet
rubber on concrete, dry
rubber on concrete, wet
rubber on ice
leather on oak, dry
1. A 70.0 kg hockey player glides across the ice on steel skates. What is the force of friction acting on his skates?
2. The driver of a 1.50 x 103 kg car applies the brakes on a concrete road. Calculate the force of friction when the car skids a) on a dry road. b) on a wet road.
3. Someone places a 250 kg trunk on a piece of carpeting and slides it along by exerting a horizontal force of 425 N. a) What is the coefficient of friction? b) What is likely to happen to the coefficient of friction if another trunk, this one with a mass of 50.0 kg, is placed on top of the bigger trunk? c) What horizontal force must the mover apply to move the combination of trunks at constant speed?
4. If the coefficient of friction is 0.30, how much horizontal force is needed to pull a mass of 15 kg across a board at a uniform velocity?
5. A cart with a mass of 2.0 kg is pulled across a level desk by a horizontal force of 4.0 N. If the coefficient of friction is 0.12, what is the acceleration of the cart? Draw a free body diagram.
6. A 10.0 kg box of books is pulled across a level floor , where the coefficient of friction is 0.350. What horizontal force is required for an acceleration of 2.00 m/s2. Draw a free body diagram.
7. A sled with waxed hickory runners rests on a horizontal surface of dry snow. Calculate the mass of sled if the maximum force that can be applied to the sled before it starts moving is 46 N [forward].
8. A 1640-kg lift truck with rubber tires is skidding on wet concrete with all four wheels locked. Calculate the acceleration of the truck if of rubber on wet concrete is 0.5.
9. An applied force of 450 N [forward] is needed to drag a 1000-kg crate at constant speed across a horizontal, rough floor. Calculate the coefficient of kinetic friction for the crate on the floor.
10. Calculate the force of kinetic friction if the lift truck in Example 15 is skidding downhill at constant speed on a hill forming an angle of 15.00 with the horizontal.
11. A pair of skies weigh 15 N…