GCSE Physics revision

Energy stores and systems

Energy changes in a system, and the ways energy is stored

AQA 4.1.1.1

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AQA student objectives

Learning pathway

All · Most · Some

ALL 🎯

Describe all the changes involved in the way energy is stored when a system changes, for common situations.

MOST 🎯🎯

Apply the scientific explanation of energy stores and systems to a relevant example.

SOME 🎯🎯🎯

Analyse a new situation involving energy stores and systems and explain the scientific reasoning.

Revision summary

Key knowledge

Read on screen, then print for Cornell-style active revision.

Kinetic Energy Store

Any object that is moving has energy in its kinetic store — the clue is simply that it is moving.
The greater the speed of an object (assuming constant mass), the larger its kinetic energy store.
Examples include a rolling football, a speeding car, and a cyclist travelling downhill.

Thermal Energy Store

When an object gets hotter, its thermal store increases — never call it a 'heat store', as heat is a method of energy transfer, not a store.
Examples include a warming frying pan, a steaming cup of coffee, or any object whose temperature is rising.
When a hot object cools down over time, its thermal store is decreasing.

2. Thermal Energy StoreAQA

Notes

When an object gets hotter, its thermal store increases — never call it a 'heat store', as heat is a method of energy transfer, not a store.
Examples include a warming frying pan, a steaming cup of coffee, or any object whose temperature is rising.
When a hot object cools down over time, its thermal store is decreasing.

Chemical Energy Store

Energy is held in the chemical store in food, fuels such as petrol, and batteries.
A very common misconception is that a battery stores electrical energy — it does not; it stores energy in its chemical store.
The chemical store involves energy held within the bonds between atoms, which is released during chemical reactions.

3. Chemical Energy StoreAQA

Notes

Energy is held in the chemical store in food, fuels such as petrol, and batteries.
A very common misconception is that a battery stores electrical energy — it does not; it stores energy in its chemical store.
The chemical store involves energy held within the bonds between atoms, which is released during chemical reactions.

Gravitational Potential Energy Store

When an object is raised to a higher position above the ground, energy is stored in its gravitational potential store.
The higher the object is above the ground, the greater its gravitational potential energy store.
This store always involves the system of the object and the Earth together, not the object alone.

4. Gravitational Potential Energy StoreAQA

Notes

When an object is raised to a higher position above the ground, energy is stored in its gravitational potential store.
The higher the object is above the ground, the greater its gravitational potential energy store.
This store always involves the system of the object and the Earth together, not the object alone.

Elastic Potential Energy Store

When an object is stretched or compressed and tends to return to its original shape, energy is stored in its elastic potential store.
The key term here is elastic deformation — the object must be able to return towards its original shape for this store to apply.
A compressed spring or a stretched rubber band are classic examples of the elastic potential store.
If an object is permanently deformed and does not return to its original shape, this is not elastic deformation and the elastic potential store does not apply.

5. Elastic Potential Energy StoreAQA

Notes

When an object is stretched or compressed and tends to return to its original shape, energy is stored in its elastic potential store.
The key term here is elastic deformation — the object must be able to return towards its original shape for this store to apply.
A compressed spring or a stretched rubber band are classic examples of the elastic potential store.
If an object is permanently deformed and does not return to its original shape, this is not elastic deformation and the elastic potential store does not apply.

Magnetic & Electrostatic Energy Stores

When magnets or magnetic materials interact with each other — such as two repelling magnets being forced together — energy is stored in the magnetic store.
When electric charges interact — such as two positive charges being forced closer together — energy is stored in the electrostatic store.
It is important to keep these two stores distinct: magnets interacting equals magnetic, and charges interacting equals electrostatic.

6. Magnetic & Electrostatic Energy StoresAQA

Notes

When magnets or magnetic materials interact with each other — such as two repelling magnets being forced together — energy is stored in the magnetic store.
When electric charges interact — such as two positive charges being forced closer together — energy is stored in the electrostatic store.
It is important to keep these two stores distinct: magnets interacting equals magnetic, and charges interacting equals electrostatic.

Nuclear Energy Store

Energy is stored in the nuclear store when changes occur to the atomic nucleus itself, as in nuclear fission or fusion.
The nuclear store must not be confused with the chemical store — chemical reactions involve atoms rearranging and changes to outer electron bonds, whereas nuclear reactions involve the nucleus.
The clue is in the name: if the nucleus is involved, it is the nuclear store.

7. Nuclear Energy StoreAQA

Notes

Energy is stored in the nuclear store when changes occur to the atomic nucleus itself, as in nuclear fission or fusion.
The nuclear store must not be confused with the chemical store — chemical reactions involve atoms rearranging and changes to outer electron bonds, whereas nuclear reactions involve the nucleus.
The clue is in the name: if the nucleus is involved, it is the nuclear store.

Situational Clues: Your Revision Toolkit

Rather than memorising eight disconnected terms, connect each real-world clue directly to its energy store to avoid confusion in exams.
Moving kinetic; getting hotter thermal; food, fuel, or battery chemical; higher up gravitational potential.
Stretched or compressed (and returns to shape) elastic potential; magnets interacting magnetic; charges interacting electrostatic; nucleus involved nuclear.

8. Situational Clues: Your Revision ToolkitAQA

Notes

Rather than memorising eight disconnected terms, connect each real-world clue directly to its energy store to avoid confusion in exams.
Moving kinetic; getting hotter thermal; food, fuel, or battery chemical; higher up gravitational potential.
Stretched or compressed (and returns to shape) elastic potential; magnets interacting magnetic; charges interacting electrostatic; nucleus involved nuclear.

Applying Your Knowledge: Exam-Style Example

For a student pulling back an elastic catapult holding a ball above the ground, two energy stores are present in the system.
The elastic potential store is present because the catapult is elastically deformed and will return to its original shape.
The gravitational potential store is present because the ball is held at a raised position above the ground, within the ball–Earth system.

9. Applying Your Knowledge: Exam-Style ExampleAQA

Notes

For a student pulling back an elastic catapult holding a ball above the ground, two energy stores are present in the system.
The elastic potential store is present because the catapult is elastically deformed and will return to its original shape.
The gravitational potential store is present because the ball is held at a raised position above the ground, within the ball–Earth system.