Using energy

- Light
- Sound
- Kinetic (movement) - a falling object transfers GP to Kinetic.
- Nuclear
- Electrical
- Gravitational potential - any object above ground has this
- Elastic potential
- Chemical

Energy can be transformed from one form to another. 

It is not possible to create or destroy energy.

This means the total amount of energy is always the same. This is called the conservation of energy.

eg. When an object falls, gravitational potential energy is transferred to kinetic energy.
Stretching an elastic band transfers chemical energy to elastic potential.

Useful energy is energy in the place and form we want it.

Wasted energy is not useful energy.

Useful and wasted energy both end up being transferred into the surroundings which become warmer.

As energy spreads out, it gets more and more difficult to use for further energy transfers.

!!! We should talk about energy being wasted and not lost because energy cannot be destroyed !!!

Efficiency = useful energy transferred / total energy supplied (x100%)

Measures done to make machines more efficient include:

- friction

- air resistance

- electrical resistance

- noise due to vibrations