A 20-N crate starting at rest slides down a rough 5.0-m long ramp, inclined at 250 with the horizontal. 20 J of energy is lost to friction. What will be the speed of the crate at the bottom of the incline? (4.7 m/s) A pile driver drives a post into the ground. The mass of the pile driver is 2 500 kg and it is dropped through a height of 8.0 m on each stroke. If the resisting force of the ground is 4.0 x 10 N, how far is the post driven in on each stroke? (4.9 cm) A girl and her bicycle have a total mass of 40.0 kg. At the top of the hill her speed is 5.0 m/s, and her speed doubles as she rides down the hill. The hill is 10.0 m high and 100 m long. How much kinetic energy and potential energy is lost to friction? (2 420 J) A horizontal force is applied to a 4.0 kg box. The box starts from rest moves a horizontal distance of 8.0 meters and obtains a velocity of 6.0 m/'s. The system is frictionless. What is the horizontal force? (9 N) A 20 kg box slides down a 12.0 m long frictionless incline at an angle of 30 degrees with the horizontal. A force of 50 N is applied to the box to try to pull it up the incline. The applied force makes an angle of 10 degrees to the incline and above the incline. What is the increase in the kinetic energy of the box? (585 J)