# 1.7.2 KE & GPE

Extended Only

### Gravitational Potential Energy

• The gravitational potential energy (GPE) of an object is the energy it has due to its height in a gravitational field:
• If an object is lifted up it will gain GPE
• If it falls, it will lose GPE

Gravitational potential energy: The energy an object has when it is lifted up

• The GPE of an object is related to its mass (m), height (h) and the gravitational field strength (g):
• The gravitational field strength (g) on the Earth is approximately 10 N/kg
(You will always be told this value in your examination paper)

Extended Only

### Kinetic Energy

• The kinetic energy (KE) of an object is the energy it has as a result of its speed

Kinetic energy: the energy an object has when it is moving

• It is related to the mass (m) and speed (v) of the object by the equation:

(Note: In the above equation only the speed is squared – not the mass or the ½)

Worked example showing how GPE transfers to KE

### Author: Jenna

Jenna studied at Cardiff University before training to become a science teacher at the University of Bath specialising in Biology (although she loves teaching all three sciences at GCSE level!). Teaching is her passion, and with 10 years experience teaching across a wide range of specifications – from GCSE and A Level Biology in the UK to IGCSE and IB Biology internationally – she knows what is required to pass those Biology exams.
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