AQA GCSE Physics

Revision Notes

1.1.4 Gravitational Potential Energy

Gravitational Potential Energy

  • The gravitational potential energy (Ep or GPE) of an object (also known as its gravitational store) is defined as:

The energy an object has due to its height in a gravitational field

  • This means:
    • If an object is lifted up it will gain Ep
    • If it falls, it will lose Ep

gpe man, IGCSE & GCSE Physics revision notes

  • The Ep of an object can be calculated using the equation:

Ep = m × g × h

  • Where:
    • Ep = gravitational potential energy, in Joules (J)
    • m = mass, in kilograms (kg)
    • g = gravitational field strength in Newtons per kilogram (N/kg)
    • h = height in metres (m)

Gravitational Field Strength

  • The gravitational field strength (g) on the Earth is approximately 10 N/kg
  • The gravitational field strength on the surface of the Moon is less than on the Earth
    • This means it would be easier to lift a mass on the Moon than on the Earth
  • The gravitational field strength on the surface of the gas giants (eg. Jupiter and Saturn) is more than on the Earth
    • This means it would be harder to lift a mass on the gas giants than on the Earth

Gravitational field strength diagram, downloadable AS & A Level Physics revision notes

Some values for g on the different objects in the Solar System

Worked Example

A man of mass 70 kg climbs a flight of stairs that is 3 m higher than the floor. Gravitational field strength is approximately 10 N/kg.

Calculate the increase in his gravitational potential energy store.

Step 1: List the known quantities

    • Mass of the man, m = 70 kg
    • Gravitational field strength, g = 10 N/kg
    • Height, h = 3 m

Step 2: Write down the equation for gravitational potential energy

Ep = mgh

Step 3: Calculate the gravitational potential energy

Ep = 70 × 10 × 3 = 2100 J

Estimating Physical Quantities, downloadable AS & A Level Physics revision notes

Exam Tip

When doing calculations involving gravitational field strength, g, don’t panic, you will always be told the value of g in your examination paper!

Author: Ashika

Ashika graduated with a first-class Physics degree from Manchester University and, having worked as a software engineer, focused on Physics education, creating engaging content to help students across all levels. Now an experienced GCSE and A Level Physics and Maths tutor, Ashika helps to grow and improve our Physics resources.
Close

Join Save My Exams

Download all our Revision Notes as PDFs

Try a Free Sample of our revision notes as a printable PDF.

Join Now
Already a member?
Go to Top