Question

You exert of force of 75 newtons on a rock. You push and you push, but you can't budge it. You are exhausted! How much work did you perform?

Answer 1

0 because (work) = (force times the distance the force is applied over) and since there is no distance, work done is 0

Answer 2

If you 're thinking about how tired you get from pushing, technically there's all kind of other work going on like from chemical reactions within your cells, but I don't think that's the point of this problem, because you'll need a lot of complicated mathematics to model bio-mechanical processes.