Every object in nature that located at certain height and gravity acting on it has potential energy. We can calculate use the equation Up=m*g*h.

The energy released when the object falls.

In elevating system we use weights that has approximately the same weight as the elevator that is connected to it by a cable around a pulley, (look at the sketch).

when the elevator is in the 3rd floor and the weights is in the 2ns floor, which of them has a higher potential energy?