The amount of work (W) done in a moving object can be found by using the following equation:

Work is expressed in units called joules (J). One joule is equal to the energy expended (or work done) when a force of one newton is applied to an object, and the object is moved a distance of one meter. So, one J is the same as 1 N • m.

Let's try some practice problems.

A crane lifts a load of logs 3 meters with a force of 5,200 Newtons. How much work did the crane do?

Interactive popup. Assistance may be required. W = FdF = 5,200 N • 3 m

F = 15,600 N • m or 15,600 J

Jake uses 45 Newtons of force to move the cart 6.5 meters. How much work did Jake do?

Interactive popup. Assistance may be required. W = FdF = 45 N • 6.5 m

F = 292.5 N • m or 292.5 J

Andy uses a force of 20 Newtons to push a lawn mower 20 meters. How much work did he do?

Interactive popup. Assistance may be required. W = FdF = 20 N • 20 m

F = 400 N • m or 400 J

A 45 kg girl sits on an 8 kg bench. How much work is done on the bench?

Interactive popup. Assistance may be required. W = FdF = 45 N • 0 m

F = 0 N • m or 0 J

No work is done in this example because the bench did not move.