Work, calculated by using [tex]W=Fs[/tex] provides us with the energy required/used. If a force is applied to a mass, but there is no displacement (due to friction/gravity/some other counteractive force) this means there is no work being done. My first issue with work is that energy is being used to create this force, but the 0 work means 0 energy. It doesn't take into account the energy required to exceed the countering forces. If a force of 1N is applied to a mass of 1kg for 1 second, its displacement will be 50cm. This calculates to be 0.5 Joules of energy. If this same force is applied for the same amount of time to the same mass now travelling at 1ms-1, the displacement will now be 150cm, so the work done is equal to 1.5 Joules. The same force was sustained on the same mass for the same time, yet in the 2nd situation there was 3x as much work done as the 1st situation. I guess it's my limited understanding of work, but this concept seems to be getting the better of me and I'm struggling to come to terms with it. My teacher can't explain it to me either, so if anyone is able to explain what is happening here, it would be much appreciated.