We can store energy and release it in different forms. Stored energy is commonly referred to as potential energy. There are many forms of potential energy, elastic, chemical and gravitational are but a few.

Chemical potential energy is stored in amongst the chemicals that we use as fuels.

Things that are high up off the ground are said to have gravitational potential energy. They have the ability to do work. The higher they are, the more work they can do for us, on the way down, therefore the more energy they have stored.

Gravitational potential energy is calculated by the formula E =mgh (m is the mass of the object in kilograms, g is a constant related to Earth’s gravitational force and is given a value of 9.8 and h is the height of the object.

E=mgh = 30 X 9.8 X 20 = 5880 Joules of energy.

An 80kg firefighter is trapped on top of a burning building. His colleagues on the ground suggest he jump. Calculate the firefighter's energy content if the top of the building is 200m high.

E = mgh = 80 X 9.8 X 200 = 156800j

= 156.8 kilojoules.