# Energy Transfer

## Key Stage 3

### Meaning

An Energy Transfer is when energy moves from one energy store to another energy store.

Energy can be transferred from one object to another or between energy stores within the same object. For example on a pool table when white ball hits another ball energy is transferred from the kinetic store of the white ball to the kinetic store of the other ball.

There are 4 ways energy can be transferred;

## Key Stage 4

### Meaning

An Energy Transfer is when energy moves from one energy store to another energy store.

Energy and be transferred between stores in a system. This may be between the different energy stores of a single object or between the energy stores of different objects within that system.
When there is an energy transfer energy is neither created, nor destroyed. This means when that when one energy store decreases, one or more others must increase.
Humans use energy transfers for a number of reasons but they usually result in some energy being transferred to an unwanted store. This is known as Wasted Energy.

There are 4 ways energy can be transferred;

### Real World Energy Transfers

When describing the energy transfers in a system the initial energy store and final energy store are stated. NB: It is important to note which object has the energy store. It is not enough to say a "Thermal Energy Store", it must be a "Thermal Energy Store of the object".

#### Going Up

When an object travels upwards the gravitational potential energy store increases.

The following are examples of energy transfers into the gravitational potential energy store:

Kinetic Energy Store of the ball → Gravitational Potential Energy Store of the ball.

Chemical Potential Energy Store of the gunpowder → Gravitational Potential Energy Store of the firework.

Elastic Potential Energy Store of the bow → Gravitational Potential Energy Store of the arrow.

#### Falling

When an object falls the gravitational potential energy store decreases.

Gravitational Potential Energy Store of the ball → Thermal Energy Store of the ball and surroundings

• A trampolinist stars at a height of 2 metres and falls onto a trampoline stretching the springs. Mechanical energy transfer due to the weight of the trampolinist and the force needed to extend the springs.

Gravitational Potential Energy Store of the trampolinist → Elastic Potential Energy Store of the trampoline.

#### Collisions

When an object collides with another object energy the kinetic energy store of the first object decreases.

Kinetic Energy Store of the white ball → Kinetic Energy Store of the red ball.

Kinetic Energy Store of the tennis ball → Elastic Potential Energy Store of the tennis ball.

Kinetic Energy Store of the sponge → Thermal Energy Store of the sponge and surroundings.

#### Acceleration by a Constant Force

When an object accelerates the kinetic energy store increases.

Chemical Potential Energy Store of the fuel/batteryKinetic Energy Store of the car.

Gravitational Potential Energy Store of the skydiver → Kinetic Energy Store of the skydiver.

#### A vehicle slowing down

When an object decelerates the kinetic energy store decreases.

Kinetic Energy Store of the carThermal Energy Store of the brakes.

Kinetic Energy Store of the ball → Thermal Energy Store of the ball and surroundings.

#### Heating

When objects are heated the thermal energy store or the Internal Energy of the object increases.

Thermal Energy Store of the stove → Thermal Energy Store of the water and kettle.

Chemical Potential Energy Store of the batteryThermal Energy Store of the water and kettle.

### Examples

 The front brakes of this car are glowing from the high temperature. Energy has been transferred by friction from the Kinetic Energy Store of the car to the Thermal Energy Store of the brakes. The high temperature of the brakes causes them to heat the air around them. Energy is being tansferred by heating from the Thermal Energy Store of the brakes to the Thermal Energy Store of the air around them. Electricity transfers energy into the Thermal Energy Store of the filament inside the bulb. The high temperature causes the bulb to glow, emitting Visible Light. This Visible Light transfers energy by radiation to the surroundings.

### References

#### AQA

Energy transfer, pages 115, 122, 290, 293-4, GCSE Biology, Hodder, AQA
Energy transfer, pages 152- 154, GCSE Combined Science Trilogy; Chemistry, CGP, AQA
Energy transfer, pages 177-179, GCSE Chemistry, CGP, AQA
Energy transfer; and work, pages 9-10, 81, GCSE Physics, Hodder, AQA
Energy transfers, page 167, GCSE Combined Science; The Revision Guide, CGP, AQA
Energy transfers, pages 11, 53. GCSE Physics; The Revision Guide, CGP, AQA
Energy transfers, pages 21, 136, GCSE Combined Science Trilogy; Physics, CGP, AQA
Energy transfers, pages 22, 156, GCSE Physics; The Complete 9-1 Course for AQA, CGP, AQA
Energy transfers, pages 261, 264-5, 282-3, GCSE Combined Science Trilogy 1, Hodder, AQA
Energy transfers, pages 37, 140-141, GCSE Chemistry; Third Edition, Oxford University Press, AQA
Energy transfers, pages 4, 7-8, 27-8, GCSE Physics, Hodder, AQA
Energy transfers, pages 5-21, 24-35, 68-71, 84-85, GCSE Physics; Third Edition, Oxford University Press, AQA

#### Edexcel

Energy transfer diagrams, page 25, GCSE Physics; The Revision Guide, CGP, Edexcel
Energy transfer, pages 178-179, GCSE Biology, Pearson, Edexcel
Energy transfer, pages 430-431, GCSE Combined Science, Pearson Edexcel
Energy transfer; stretching, page 199, GCSE Physics, Pearson Edexcel
Energy transfer; stretching, page 431, GCSE Combined Science, Pearson Edexcel
Energy transfers (in ecosystems), pages 289, 292, GCSE Biology, CGP, Edexcel
Energy transfers (in ecosystems), pages 97, 98, GCSE Biology; The Revision Guide, CGP, Edexcel
Energy transfers, page 392-393, GCSE Combined Science, Pearson Edexcel
Energy transfers, pages 157, 159, 179, GCSE Combined Science; The Revision Guide, CGP, Edexcel
Energy transfers, pages 25, 27, 65, GCSE Physics; The Revision Guide, CGP, Edexcel
Energy transfers, pages 34-35, 152-153, 198-199, GCSE Physics, Pearson Edexcel
Energy transfers, pages 61-65, 68, 197-204, GCSE Physics, CGP, Edexcel
Energy transfers; by heating, pages 198, 243, GCSE Physics, CGP, Edexcel
Energy transfers; by waves, page 88, GCSE Physics, CGP, Edexcel
Energy transfers; diagrams, pages 65, 72, 197, GCSE Physics, CGP, Edexcel
Energy transfers; efficiency, pages 71-73, GCSE Physics, CGP, Edexcel
Energy transfers; electricity, pages 156-157, GCSE Physics, Pearson Edexcel
Energy transfers; electricity, pages 396-397, GCSE Combined Science, Pearson Edexcel
Energy transfers; in electrical appliances, pages 198, 242, 243, GCSE Physics, CGP, Edexcel
Energy transfers; in power stations, page 176, GCSE Physics, CGP, Edexcel