Gravitational potential energy is the energy an object has due to its position in a gravitational field. Lift a book onto a shelf and it gains potential energy. The higher it is, the more energy it has. Drop it and the energy converts to kinetic energy. The book falls faster and faster until it hits the floor.

The formula is mass times gravitational acceleration times height. Double the height and the energy doubles. Double the mass and the energy doubles. The reference point is arbitrary. You can measure height from the floor, from sea level, or from the center of the Earth. Only the change in height matters. The energy difference between two positions is what counts.

Gravitational potential energy examples

• A book on a shelf.
• Water behind a dam.
• A roller coaster at the top of a hill.
• A satellite in orbit.
• A person at the top of a staircase.

Gravitational potential energy is stored energy. It is waiting to be released. A hydroelectric dam holds water at a high elevation. The water flows down through turbines, converting potential energy to electrical energy. A roller coaster uses the same principle. The chain lift raises the cars to the top of the first hill. Gravity does the rest. The energy is not created. It is transformed. The total energy in a closed system is conserved. Potential energy becomes kinetic energy becomes heat and sound. The math is simple. The consequences are enormous. Every falling object, every flowing river, every orbiting moon is a lesson in gravitational potential energy.