1. A 5200 kg train is pulled 360m along a 12 degree incline. What is the change in potential energy of the train?

2. A 60 kg person stands on a platform 2 m above a 4 m deep pool.

a. What is the potential energy of the person with respect to the top surface of the pool?

b. With respect to the bottom of the pool?

3. A BMW is equipped with a spring loaded bumper designed to compress 0.3 m when it contacts a wall at 9m/s. The spring must absorb 8 x 10⁴ J of energy to prevent damage to the car. What should the spring constant be?

4. A spring has a 500 N/m spring constant. What is the spring's potential energy when:

a. it is stretched 4cm from equilibrium?

b. it is not stretched?

c. it is compressed 3 cm from equilibrium?

5. A spring is stretched 6 cm from equilibrium. If it has a 1.2 x 10⁴ N/m spring constant:

a. what is its change in potential energy?

b. what is its change in potential energy as it moves from 6 cm to 3 cm from equilibrium?

c. what is its change in potential energy as it moves from 3 cm to equilibrium?