The gravitational potential energy is the energy stored in an object due to its position in the gravitational field. Mathematically, it is defined as the product of an object’s weight and height above the ground. Thus, the gravitational potential energy of a ball of mass m hanging at a height y from the ground is mgy. For example, in ice hockey, if a puck of mass m takes a parabolic path after the shot, then the gravitational potential energy at point B is mgy, where y is the height of the puck from the ground. When the puck moves from point A to B, the change in gravitational potential energy is positive as the gravitational potential energy increases and is equal to the negative of the work done. Similarly, when the puck moves from point B to C, the gravitational potential energy decreases, and the work done by the gravitational force is positive. Thus, when a body moves upwards, the gravitational potential energy increases and decreases when the body moves downwards.