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A long way down…

How would you describe a high diver? As someone who is:

full of gravitational potential energy (GPE).

brave

insane

full of beans

GPE is the amount of energy an object has because of its position above the ground, i.e. its height.

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When a bungee jumper starts to fall he starts to lose GPE.

As the elastic cord pulls the bungee jumper back up, he gains GPE.

The gravitational potential energy (GPE) of an object on Earth depends on its mass and its height above the Earth’s surface.

What is gravitational potential energy?

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How is GPE calculated?

The GPE of an object can be calculated using this equation:

GPE = mass x gravitational field strength x height

Height is measured in metres (m).

Mass is measured in kilograms (kg).

GPE is measured in joules (j).

Gravitational field strength is measured in newtons per kilogram (N/kg), usually taken as 10 N/kg on Earth.

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Factors affecting GPE

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An osprey with a mass of2 kg flies at a height of200 m above the ground.

Calculating GPE question 1

How much gravitational potential energy does the osprey have?

= 2 x 10 x 200

GPE = mass x gravitational field strength x height

= 4,000 J

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An apple with a mass of 200 g falls 3 m from its branch to the ground.

Calculating GPE question 2

How much GPE will the apple have lost when it reaches the ground?

= 0.2 x 10 x 3

= 6 J

= mass x gravitational field strength xGPElost

changein height

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GPE, mass and height calculations