A 2.00-kg mass is attached to a vertical spring with a spring constant of 250 N/m. A student pushes on the mass vertically upward with her hand while slowly lowering it to its equilibrium position.
(a) How many forces do nonzero work on the object: (1) one, (2) two, or (3) three? Explain your reasoning.
(b) Calculate the work done on the object by each of the forces acting on it as it is lowered into position.