Physics 8463 - 4.5 Forces

When a force causes an object to move through a distance work is done on the object.

So a force does work on an object when the force causes a displacement of the object.

The work done by a force on an object can be calculated using the equation:

work done = force × distance moved along the line of action of the force

W = Fs

This equation is NOT given on the Physics equation sheet - you need to know it, what the letters mean and are measured in!

W = work done, in joules, J

F = force, F, in newtons, N

s = displacement (the distance moved along the line of action of the force), in metres, m

Note that 's' is displacement - it it different from 'd' for distance (see vectors).

One joule of work is done when a force of one newton causes a displacement of one metre.

1 joule = 1 newton-metre

1 J = 1 Nm

You should be able to describe the energy transfer involved when work is done, and should be able to convert between newton-metres and joules.

Work done against the frictional forces acting on an object causes a rise in the temperature of the object as kinetic energy is transferred to heat.