Conservative and Nonconservative Forces
1) A 0.60 kg basketball is thrown from a height 2.5 m above the floor with a speed of 7.2 m/s. The ball goes through the net 3.0 m above the floor with a speed of 4.3 m/s. How much work was done on the ball by air resistance?
2) A 375 kg roller coaster is pulled up a hill by a chain that does 3.00 × 104 J of work. As the car is moving up the hill, friction does – 2.00 × 104 J of work. If the coaster starts 5.00 m above the ground and finishes 20.0 m above the ground, what is its change in kinetic energy?
3) A 74.0 kg student starts from rest and slides down a water slide 11.8 m high. On the way down, friction does – 5.60 × 103 J of work on him. How fast is he going at the bottom of the slide?
4) A 5.00 × 102 kg hot-air balloon starts at rest on the surface of the earth. Nonconservative forces (i.e. wind and lift) raise the balloon off the ground, doing 9.70 × 104 J of work. At what height will the balloon have a speed of 8.00 m/s?