Power & Velocity

The expression (F × s) ÷ t, representing work done ÷ time taken is also equal to force × velocity. This gives an alternative way of calculating power in situations where the force and speed in the direction of the force (the component of the velocity in that direction) are known:

Power = force × velocity
P = F v

This expression can be applied to the motive power of a vehicle, where F is the driving force and v is the speed of the vehicle.

For example, if a force of 600 N is used to tow a trailer at a speed of 12 m s–1, then the motive power required is 600 N × 12 m s–1 = 7200 W.