Question

A ball is dropped from the roof of a building. the mass of the ball is 3.0 kg. what is the potential energy of the ball in the instant that it is exactly 18.0 meters above the ground?

Answer 1

According to given condition there is no height(m) given from roof of building to the ground, there height given 18 m at a point above the ground.                         So, h=18m  ,                mass=3kg     ,         g=9.8m/s2                                                                      P.E=mgh                                                                                                                P.E=(3)(9.8)(18)                                                                                                      P.E=529J