Work and power
Whenever 'work' is done energy is transferred from one place to another. The amount of work done is expressed in the equation: work done = force x distance.
Power is a measure of how quickly work is being done. Power is expressed in the equation: power = work done / time taken.
Work is done whenever a force moves something.
Everyday examples of work include walking up stairs, or lifting heavy objects. Whenever work is done energy is transferred from one place to another. Both energy and work are measured in joules, J.
work done (joules, J) = energy transferred (joules, J)
The amount of work done depends on:
work done (joule, J) = force (newton, N) x distance (metre, m)
How much work is done when a man lifts a box weighing 200N off the floor to a shelf 2m high?
Work done = force x distance = 200N x 2m = 400J
Use the triangle to help you rearrange the equation to:
force = work done / distance
distance = work done / force
Check your understanding of this by having a go at the activity.