A block of mass m is released from rest at the top of an incline that makes an angle a with the horizontal. The coefficient of kinetic friction between the block and incline is mk. The top of the incline is a vertical distance h above the bottom of the incline. Derive an expression for the work Wf done on the block by friction as it travels from the top of the incline to the bottom. When a is decreased, does the magnitude of Wf increase or decrease?

A 100 kg crate is being pushed across a horizontal floor by a force that makes an angle of 30.0° below the horizontal. The coefficient of kinetic friction is 0.2. What should be the magnitude of the force, so that the net work done by it and the kinetic frictional force is zero?

A box slides down a plank of length d that makes an angle of θ with the horizontal as shown. μk is the kinetic coefficient of friction and μs is the static coefficient of friction. Enter an expression for the minimum angle θ (in degrees) the box will begin to slide.  Enter an expression for the nonconservative work done by kinetic friction as the block slides down the plank. Assume the box starts from rest and θ is large enough that it will move down the plank.  For a plank of any length, at what angle θ (in degrees) will the final speed of the box at the bottom of the plank be 0.55 times the final speed of the box when there is no friction present? Assume μk = 0.35.

A 200 gram hockey puck is launched up a metal ramp that is inclined at a 45° angle. The coefficients of static and kinetic friction between the hockey puck and the metal ramp are μs = 1.60 and μk = 1.50, respectively. The puck's initial speed is 6 m/s.   (a) The vertical height reached by the puck above its starting point is _______ (b) The net work done on the hockey puck is ______

A box slides down a plank of length d that makes an angle of θ with the horizontal as shown. μk is the kinetic coefficient of friction and μs is the static coefficient of friction. a) Enter an expression for the minimum angle θ (in degrees) the box will begin to slide.  b) Enter an expression for the nonconservative work done by kinetic friction as the block slides down the plank. Assume the box starts from rest and θ is large enough that it will move down the plank.

A hockey puck of mass 0.26 kg is sliding along a slippery frozen lake, with an initial speed of 64 m/s. The coefficient of friction between the ice and the puck is eventually causes the puck to slide to a stop. Find the work done by friction. J = 0.031. Friction

A block of mass m slides down an inclined plane with angle θ up from the horizontal. The block-surface interface has a kinetic friction of μk. If the block slides a distance d, what is the total work done on it by all forces?

A 1680 kg car skids on a level road with coefficient of kinetic friction 0.64 between the tires of the car and the road.  The car skids a distance of 102 m and comes to a complete stop.  The work done on the car by the force of kinetic friction is (enter your answer with two significant figures) possibly useful: W = (Fcosθ)d w = mg g = 9.81 m/s2

A collie drags its bed box across a floor by applying a horizontal force of 8.0 N.The kinetic frictional force acting on the box has magnitude 5.0 N. As the box is dragged through 0.70 m along the way, what are (a) the work done by the collie’s applied force and (b) the increase in thermal energy of the bed and floor?

A trunk of mass m = 0.6 kg is pushed a distance d = 30 cm up an incline with an angle of inclination theta = 23.0° by a constant horizontal force P = 425 N (see figure). The coefficient of kinetic friction between the trunk and the incline is 0.31. P. Calculate the work done on the trunk by the applied force P. Calculate the work done on the trunk by the frictional force. Calculate the work done on the trunk by the gravitational force.