1. A 10.5 kg sled starts from rest at the top of a hill that is inclined at 21.6 degrees to the horizontal. The sled travels along the incline for a distance of 15.8 m to the foot of the hill where it has speed of 8.0078371895854 m/s. Find the work done by friction on the sled. 2. A 1683 kg sports car goes from 0 to 25.8 m/s in 4.55 s. What is the average power deliver by the engine if the work done by friction is a 0.11 of the final kinetic energy? 3. A child slides down from the top of a slide 9.0 meters high. If 0.25 of the total energy is lost to friction, find the velocity with which she exists at the bottom. 4. A stone S1 is dropped from a height of 23.4 m while a second stone S2 is dropped from a height 4.5. If air resistance is negligible, what is the ratio of the speeds of the stones $2:51 when they each reach the ground (instant before impact). 5. A 22.3 kg sled starts from rest at the top of a hill that is inclined at 19.0 degrees to the horizontal. The sled travels along the incline for a distance of 7.0 m to the foot of the hill where it has speed of 5.0793905517476 m/s. Find the work done by gravity on the sled. 6. A 5.3 kg object is accelerated from rest to 17.5 m/s. Find the work done by the force acting on the object during the acceleration. 7. To win a prize at the fair you must throw a ball upward to the target. The ball must hit the target with a speed of 6 m/s and the target is 19.8 m above the point where the ball leaves your hand. If you can ignore air resistance, find the speed with which the ball must leave your hand