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Science

Work and power

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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 and force

Work done

Work is done whenever a force moves something.

10 N force applied -> Box moved by 2m

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:

  • the size of the force on the object
  • the distance the object moves

Equation

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

Higher tier

Work done = Force x Distance

Use the triangle to help you rearrange the equation to:

force = work done / distance

distance = work done / force

Rearranging equation activity - higher tier only

Check your understanding of this by having a go at the activity.

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