Object A has a gravitational potential energy of 24 joules when it rests on a shelf 5m above the ground. Object B has a mass that is three times the mass of Object A. What would be the gravitational potential energy of object B when it rests on a shelf 10m above the ground?

Potential energy = (mass) (gravity) (height)

Potential energy is directly proportional to mass and also to height.

Object-B has 3 times the mass, and 2 times the height of object-A.

So its potential energy is (3 x 2) = 6 times the PE of object-A.

6 times (24 joules) = 144 joules.