I sort of need help conceptualizing how this energy system would work. There is a boulder on the ground and a person is attempting to move it by pushing it. However, because of the static friction, the boulder does not move and ultimately, no work is done. However, there must have been some energy transfer since after some time, the person feels tired. If the energy transfer were written as: Wp - Wf = Wnet (Wp - work done by person, Wf, work done by static friction, and Wnet - net work), then it could be stated as 0 - 0 = 0. I'm assuming this implies that the energy transfer was not mechanical. The problem here is that, if the person doesn't move the boulder, then there is no work done, and since static friction doesn't accelerate the boulder, no work is done by that either. So then, what was the energy transfer going on here? And also, does static friction influence energy systems (does it process energy into heat, etc...?).