Work: Work is said to be done when a force of 1N moves an object through a distance of 1m in the direction of the force.

NB: No work is done if the force does not produce motion. Hence, only unbalanced forces do work or produce work. Work done can be calculated from the formula below;

Workdone(W)=Force(F)*Distance(S)

W=F*S

The S.I unit for work done is the joule (J), newton meter (Nm).

Example: A girl uses a force of 400N to push a box across a horizontal floor through a distance of 200m.

Solution

W=F*S               But F=400N, S=20cm = 0.20m

W= 400N*0.20m = 80J

W=80J

Example of Situations Involving Work done

1. A girl pushing or pulling a box across horizontal floor.
2. A boy climbing stairs.

Special Cases of Work done

• Work done on an inclined plane:

Work done=F*Scosθ