Answer to Question #245258 in Physics for Kiel

Question

A rock weighs 100 kg sitting on top of a hill 20 m high . What is the potential energy of the rock

Answer 1

The potential energy of block relative to the ground is

$$E=mgh=100·9.8·20=19600\text{ J}.$$

Relative to the top of the hill it is zero because the height above the top is zero.