Energy transfers
Pathways for transferring energy
Energy can be transferred from one store into another - as one store empties, another store fills. The process by which this happens is called the pathway. There are four main pathways:
- 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
Systems and stores
The capacity of a system to do work or the quantity required for mechanical work to take place. Measured in joules (J). For example, a man transfers 100 J of energy when moving a wheelbarrow. can remain in the same store for millions of years or sometimes just for a fraction of a second. There are energy transfers going on all the time - whenever a An object or group of objects. changes there is a change in the way some or all of the energy is stored.
Image caption, A swinging pirate ship ride at a theme park
Kinetic energy is transferred into gravitational potential energy
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A car driver braking in an emergency - kinetic energy is transferred into thermal energy of the surroundings by the work done by the force of friction on the brakes.
A snowball hitting a wall - kinetic energy is transferred into thermal energy of the surroundings by the work done by the force from the wall.