1. A 1,000-W motor powers a hoist used to lift cars at a service station.

(a) How much time would it take to raise a2,450-kg car2m?

(b) If the original motor is replaced with one rated at 3,000 W, how long would it take to complete this task?

2. A running back with a mass of 90 kg and a velocity of 9 m/s (toward the right) collides with, and is held by, a 135-kg defensive tackle going in the opposite direction (toward the left). What is the velocity of the tackle before the collision for their velocity afterward to be zero? (Remember, velocity is a vector)

3. It takes 110 minutes for a middle-aged physics professor to ride his bicycle up the road to Alpe d'Huez in France. The vertical height of the climb is 1,120 m, and the combined mass of the rider and bicycle is 86 kg. What is the bicyclist's average power output?

4. A bicycle and rider going 15 m/s approach a hill. Their total mass is 77 kg.

(a) What is their kinetic energy=8662.5 J

(b) If the rider coasts up the hill without pedaling, how high above its starting level will the bicycle be when it finally rolls to a stop?