Energy transfers

can remain in the same store for millions of years before it is transferred, sometimes just for a fraction of a second. Energy transfers happen all the time - whenever a changes, there is a change in the way some or all of the energy is stored.

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Image caption,
A swinging pirate ship ride at a theme park
A kinetic energy store is transferred to a gravitational energy store
Image caption,
A boat being accelerated by the force of the engine
As the boat pushes through the water, a chemical energy store in the fuel is transferred to the kinetic energy store of the boat and the water
Image caption,
Bringing water to a boil in an electric kettle
Electricity supplied to the kettle increases the thermal energy store of the element, which increases the thermal energy store of the water. This increases the temperature of the water.

Transferring energy

In each of these examples energy is transferred by one of the following four types of energy transfer:

mechanical work - a force moving an object through a distance
electrical work - charges moving due to a potential difference
heating - due to temperature difference caused electrically or by chemical reaction
radiation - energy transferred as a wave, eg light and infrared - the Sun emits light radiation and infrared radiation

Doing 'work' is the scientific way of saying that energy has been transferred. For example, a grazing cow, a firing catapult and a boiling kettle are all doing 'work' because energy is being transferred from one store to another.

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Energy stores and transfers - OCR GatewayEnergy transfers