On a standard pulley, on one end of the rope hangs a mass equal to a person's weight. That person is climbing up on the other end of the rope at constant speed. My guess is that the man and the mass will rise up at the same speed. And does the conservation of momentum apply in this case? How does the conservation of momentum work if a case is in a similar situation? For example, a man walking on a plank of wood of his equal weight on frictionless ice. Relative to the ground, the man is moving at half of his walking speed. Let's say you are swinging on a swing, and suddenly fly off at the lowest point of the swing path tangentially and leave the swing seat. Now in this case, the conservation of momentum applies, but not the conservation of energy. In this "reverse inelastic collision", (as I like to think of it as) where does the energy go?