Our physics instructor assigned us an extra credit assignment using vPython to make an animated system. The system needs to be something to complex for us to do by hand. Right now I'm deciding what my topic should be. I think I'd like to do something about a system involving a runner. My question is what are all the forces that act on a system of someone running around a track. I know there is +FN, -mg, -Fdrag, -Ffriction. I'm certain there is more to consider. Would anyone like to fill me in?