Hm just having a little problem with this which should only take a second to check, trust me I have used the search function/wikipedia but it's difficult to find a concise answer. If i were to raise a 1kg weight 1 meter, according to [tex] W = F.d [/tex] I will have done 1J of work, fine however I think this is 1J against gravity. Because according to the work-energy theorum no work is done, as the kinetic energy remains the same, fine. from what I understand this stems from the fact that as I raise it i (providing an upwards force + 1m upwards) am doing positive work, however gravity (acting downwards but moving it upwards) is doing equal negative work. So total work done [tex] mgh - mgh = 0 [/tex] However, now it has gained potential energy, and if I were to drop it gravity does positive work on it equal to the potential energy it had. Obviously energy is still conserved so I have no issue there but the real question is simply this; does work done not have to be conserved? or is there a better way of thinking about it? because potential energy is not taken account of as far as i can see with Work... thanks, I know i've gone on abit here and wasn't very clear, and it is a very simple question but would be nice to have it cleared up!