91热爆

The work done equation

When a causes a body to move, work is being done on the object by the force. Work is the measure of energy transfer when a force 'F' moves an object through a distance 'd'. So when work is done, has been transferred from one energy store to another, and so:

energy transferred = work done

Energy transferred and work done are both measured in joules (J).

Learn more on work done and energy transfer in this podcast

Calculating work done

The amount of work done when a force acts on a body depends on two things:

  • the size of the force acting on the object
  • the through which the force causes the body to move in the direction of the force

The equation used to calculate the work done is:

work done = force 脳 distance

\(W = F \times d\)

This is when:

  • work done (W) is measured in joules (J)
  • force (F) is measured in newtons (N)
  • distance (d) is in the same direction as the force and is measured in metres (m)

Example

A man pushes a box with a force of 10 newtons to move it a distance of 2 metres

In this example, a force of 10 N causes the box to move a horizontal distance of 2 m, so:

\(W = F \times d\)

\(W = 10 \times 2\)

\(W = 20~J\)

Question

12,000 J of energy is supplied to move a small truck a distance of 80 m. What is the size of the force applied?