Hi. I'm doing a Physics degree at the moment, and all textbooks seem to talk about work done by a force judged either by the displacement of an object (W = Fs), or its change in velocity (W = /\Etrans). In both cases, the energy given is kind of after the event. Search as I may, I cannot find an equation for the energy supplied by a force. For instance, two particles of equal mass, one with charge the other neutral, have the same force acting on them. The neutral particle will undergo a change in velocity and possibly potential energy. The charged particle though will also radiate EM energy. This energy must come from somewhere: either its kinetic energy, which would seem to increase its inertia and make it appear more massive; its mass energy, which would lead to a decrease in inertia leading to further acceleration leading to further EM radiation etc, or the energy supplied by the force. With the first two leading to paradoxes, I assume the third is true. Can anyone point me in the right direction? A classical mechanics answer would be preferred, but I'll take what I can get.