Work

Work done is a measure of the energy transferred when a force moves an object through a distance. Mechanical work and electrical work both obey the same principle: the work done equals the energy transferred. This means that calculating work done and calculating energy transferred are the same operation expressed in different contexts. The SI unit for both work done and energy transferred is the joule (J).

W = Fd = ΔE

Force must be in newtons (N) and distance must be in metres (m) for the answer to come out in joules (J).

Work done is directly proportional to both force and distance, so doubling either quantity doubles the work done.

If a force acts but the object does not move in the direction of that force, no work is done and no energy is transferred mechanically.

Exam tip Always check that the distance used is the distance moved in the direction of the applied force, not simply any distance the object happens to travel.