Kinetic and Potential Energy Explained
Energy is the ability to do work. Two of the most important types you meet at school are kinetic and potential energy, and understanding how they swap back and forth explains a huge amount of physics.
Kinetic energy: the energy of motion
Anything that is moving has kinetic energy — a rolling ball, a running person, a falling raindrop. The faster something moves and the heavier it is, the more kinetic energy it has.
Potential energy: stored energy
Potential energy is stored, waiting to be released. Gravitational potential energy depends on height — a book on a high shelf has more than one on the floor. A stretched spring or a drawn bow also stores potential energy.
Conservation of energy
Energy cannot be created or destroyed, only transferred. When you drop the book, its potential energy converts into kinetic energy as it falls. On a roller coaster, energy swaps between potential (at the top) and kinetic (at the bottom) the whole way round.
Frequently asked questions
What is kinetic energy?
The energy an object has because it is moving. More mass and more speed mean more kinetic energy.
What is potential energy?
Stored energy due to an object’s position or condition, such as height or a stretched spring.
Can energy be destroyed?
No. Energy is conserved — it only changes from one form to another.