A portable CD player uses a current of 7.2 mA at a potential difference of 3.5 V.
Suppose the player has a mass of 0.47 kg. How long could the player operate (in minutes) on the energy required to lift it through a height of 1 m?
The energy required to lift the player through a height of 1 m = m * ...
This solution looks at the relation between electrical energy and potential energy of a CD player.