By how much does the gravitational potential energy of a 58-kg pole vaulter change if her center of mass rises 4.0 m during the jump?

You drop a basketball from a height of 5.0 m, which rebounds to a new height of 3.0 m. How much energy is lost to nonconservative forces? Give your answer as percentage of the initial energy.

A 66.5-kg hiker starts at an elevation of 1150 m and climbs to the top of a peak 2660 m high. What is the hiker’s change in potential energy?