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

Energy 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 system changes there is a change in the way some or all of the energy is stored.

Boat suspended from column, swings in circular arc. Highest point: no kinetic energy,  max gravitational potential energy. Lowest point: max kinetic energy, minimum gravitational potential energy.

A swinging pirate ship ride at a theme park

Kinetic energy is transferred into gravitational potential energy

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.