GCSE Physics revision

Work done and energy transfer

AQA 4.5.2

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AQA student objectives

Learning pathway

ALL 🎯

Describe the energy transfer involved when work is done.

MOST 🎯🎯

Apply the scientific explanation of work done and energy transfer to a relevant example.

SOME 🎯🎯🎯

Analyse a new situation involving work done and energy transfer and explain the scientific reasoning.

Revision summary

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

The most fundamental principle in physics is that energy is never created or destroyed
— it is only ever transferred between different forms and objects.
This principle of conservation of energy underpins a huge proportion of the A Level
Physics course.

Thermal (internal) energy is the heat energy trapped within an object and is related to its temperature.
Kinetic energy is associated with the movement or motion of an object.
Gravitational potential energy is the energy an object possesses due to its position within a gravitational field.
Elastic potential energy is stored in a deformed object, such as a stretched or compressed spring.
Chemical energy is held within chemical bonds, magnetic energy acts between magnetic objects, electrostatic energy arises from charged objects, and nuclear energy is released when atomic nuclei are split or fused.

2. Energy StoresAQA

Thermal (internal) energy is the heat energy trapped within an object and is related to its temperature.
Kinetic energy is associated with the movement or motion of an object.
Gravitational potential energy is the energy an object possesses due to its position within a gravitational field.
Elastic potential energy is stored in a deformed object, such as a stretched or compressed spring.
Chemical energy is held within chemical bonds, magnetic energy acts between magnetic objects, electrostatic energy arises from charged objects, and nuclear energy is released when atomic nuclei are split or fused.

Energy can be transferred mechanically (e.g. physically stretching an elastic band), electrically (e.g. plugging a device into a socket), by heating, or by radiation such as light or sound waves.
The energy within any given store is not fixed — it can be transferred to another store through one of these pathways.

3. Transferring Energy Between StoresAQA

Energy can be transferred mechanically (e.g. physically stretching an elastic band), electrically (e.g. plugging a device into a socket), by heating, or by radiation such as light or sound waves.
The energy within any given store is not fixed — it can be transferred to another store through one of these pathways.

A system is the term used in physics to describe a defined collection of matter being studied.
In an open system, matter and energy can be exchanged with the outside world, meaning the system can gain or lose energy.
In a closed system, neither matter nor energy can enter or leave, so the total energy of the system always remains constant even though energy may be transferred internally.

4. Systems: Open and ClosedAQA

A system is the term used in physics to describe a defined collection of matter being studied.
In an open system, matter and energy can be exchanged with the outside world, meaning the system can gain or lose energy.
In a closed system, neither matter nor energy can enter or leave, so the total energy of the system always remains constant even though energy may be transferred internally.

When a kettle is switched on, electrical energy from the socket is transferred electrically to the thermal energy store of the heating element, warming the metal.
The heating element then transfers energy to the thermal energy store of the water, eventually bringing it to the boil.
This example illustrates how energy passes through a chain of stores via different transfer pathways.

5. Energy Transfer in Practice: The Kettle ExampleAQA

When a kettle is switched on, electrical energy from the socket is transferred electrically to the thermal energy store of the heating element, warming the metal.
The heating element then transfers energy to the thermal energy store of the water, eventually bringing it to the boil.
This example illustrates how energy passes through a chain of stores via different transfer pathways.

Work done is another way of expressing the amount of energy transferred, and there are two main types: mechanical and electrical.
Mechanical work done involves using a force to move an object, for example kicking a ball transfers energy from the chemical store of your muscles to the kinetic store of the ball.
Electrical work done occurs when a current flows through a circuit, representing the energy required to overcome the resistance in the wires.

6. Work DoneAQA

Work done is another way of expressing the amount of energy transferred, and there are two main types: mechanical and electrical.
Mechanical work done involves using a force to move an object, for example kicking a ball transfers energy from the chemical store of your muscles to the kinetic store of the ball.
Electrical work done occurs when a current flows through a circuit, representing the energy required to overcome the resistance in the wires.

When a train applies its brakes, friction acts between the brakes and wheels — we say friction does work on the train.
This work done by friction causes energy to be transferred from the kinetic energy store of the wheels to the thermal energy stores of the surroundings as heat.
This real-world example demonstrates how work done by a force results in a measurable transfer of energy between stores.

7. Work Done in Practice: The Train ExampleAQA

When a train applies its brakes, friction acts between the brakes and wheels — we say friction does work on the train.
This work done by friction causes energy to be transferred from the kinetic energy store of the wheels to the thermal energy stores of the surroundings as heat.
This real-world example demonstrates how work done by a force results in a measurable transfer of energy between stores.