Is what I am currently reading about. The book I am reading presents it by giving an example; it proposes lifting a mass without any acceleration through a height, h, with an upward force equal and opposite to its weight. Does that mean the net work done on this mass is zero? My hand still does work on the mass as well as gravity, but the amount of work does is zero, right? Also, where does the mass get its potential energy from? I know its position contributes to its potential energy, but what about the energy I use to to lift it up? Does the energy I use transfer and convert into potential energy as I lift the mass up?