Sliding a block on a floor that has friction. Going from points A to B to C to D then back to A. points ABCD make a rectangle. Moving the block at a constant speed. What is the work done by the closed loop? Since speed is a constant, then there isn't a change in KE, so then work done has to be zero right? What if I did this on a frictionless table? Would the work done be zero as well?