A force does work when it moves an object through a distance in the direction of the force. Work done equals energy transferred: W = Fs, with force in newtons, distance in metres and work in joules. When work is done against friction, energy is transferred to thermal stores. A force can act without doing work if there is no displacement. Example: A force does 240 J of work over 6 m. Calculate the force. F = W/s = 240/6 = 40 N, assuming force is parallel to the displacement. Check your reasoning.