Work done is the same as energy transferred. Conservation of energy links GPE, KE and work done. Power is the rate of transfer of energy or the rate of doing work.

Work is done whenever a force moves something.

Everyday examples of work include walking up stairs, lifting heavy objects, pulling a sledge and pushing a shopping trolley. Whenever work is done, energy is transferred from one place to another.

Here is the equation that relates work done, force applied, and distance moved in the direction of the force:

\[work~done = force \times distance\]

\[W = F \times d\]

where:

*W* is measured in joules, J

*F* is measured in newtons, N

*d* is measured in metres,m

In the example above, 10 N is applied to move the box 2 m.

Work done = **10 × 2 = 20 J**

The triangle above may help you to rearrange the equation.

Work done has the same units as energy – joules. This is because energy is the ability to do work. So you must have energy to do work. You do not have to do work if you have energy though (potential energy does not do work). Specifically, a person could not push the box (and so do work) in the example above without energy. Work done is equal to energy transferred.