Energy Stores and Systems — AQA GCSE Physics
Energy is stored in different ways and transferred between stores when a system changes.
Energy stores
A system is an object or group of objects. Energy can be stored in several ways:
- Kinetic — energy of a moving object.
- Gravitational potential — energy of a raised object.
- Elastic potential — energy in a stretched or compressed spring.
- Thermal (internal) — energy of a hot object.
- Chemical, nuclear, magnetic and electrostatic stores.
Energy transfers
When a system changes, energy is transferred between stores. Energy can be transferred:
- mechanically (by a force doing work),
- electrically (by a current),
- by heating, or
- by radiation (e.g. light or sound waves).
Examples
- An object falling: gravitational potential → kinetic store.
- A car braking: kinetic → thermal store (friction in the brakes).
- Boiling a kettle: electrical → thermal store of the water.
Conservation of energy
Energy is never created or destroyed — only transferred between stores, stored, or dissipated. The total energy of a closed system stays the same.
Exam tips
- Learn the names of the energy stores (not "types").
- Describe transfers as going from one store to another.
- Identify the transfer pathway: mechanical, electrical, heating or radiation.
- Energy is always conserved.