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So, an object held above the ground has GRAVITATIONAL potential energy (G.P.E).
A simpler word for this would be POSITION ENERGY.
To move a mass m up to a height (h) above the ground you will need to move a force F (= mg) through a distance h. This needs mgh joules of energy.

Its gravitational potential energy is mgh and it will release that energy when it falls back to the ground. (g = 10 N/kg on the Earth).

Gravitational potential energy = mass x g x height

You should realise that it does not matter which route a mass takes when falling to the ground or the route by which a box gets to the back of the lorry. The potential energy change will be the same by whatever route.

© Keith Gibbs 2008