This unit can be used for a variety of purposes to illustrate energy transfers:
it can be used to lift a mass or stretch a bungee cord, and to generate an
electrical current when the mass falls again or the bungee cord is released.
It can also be turned by hand to generate a current. The motor/generator
(6-9V) is mounted on a robust metal base, and the gearing of the unit and
the sizes of the pulleys have been chosen to enable a variety of qualitative
and quantitative experiments to be undertaken.