Conservation of Energy Sample Problems

1. An electrical motor lifts a 575 N box 20 meters straight up by a rope with constant velocity for 10.0 s. What power is developed by the motor?

2. Starting from rest, a child zooms down a frictionless slide from an initial height of 3.0 m. What is her speed at the bottom of the slide? Assume she has a mass of 25.0 kg.

3. An amusement park roller coaster car has a mass of 250 kg. During the ride, it is towed to the top of a 30 m hill, where it is released from rest and allowed to roll. The car plunges down the hill, then up a 10 m hill and through a loop with a radius of 10 m. Assume that the tracks are frictionless.

a. What is the Potential Energy of the car at the top of the 30 m hill?

b. What is the Kinetic Energy and the speed of the car at the bottom of the 30 m hill?

c. What is the Kinetic Energy and the speed of the car at the top of the 10 m hill?