Gravitational Field Strength: IGCSE Physics Definition

Written by: Ann Howell

Published

28 February 2025

Last updated

28 February 2025

In IGCSE Physics, gravitational field strength is defined as the force per unit mass acting on an object in a gravitational field.

On Earth, this is equal to $9.8 N / kg$ . The gravitational field strength acting on an object is calculated using the equation

$g = \frac{W}{m}$

Where:

$g$ = gravitational field strength, measured in newtons per kilogram ( $N / kg$ )
$W$ = force of weight, measured in newtons ( $N$ )
$m$ = mass of object, measured in kilograms ( $kg$ )

An object in free fall in a vacuum, in a uniform gravitational field, will accelerate at a rate of $g$

Where $g$ = acceleration of free fall

In this context, $g = 9.8 m / s^{2}$

Gravitational field strength and acceleration of free fall are equivalent quantities.

Some exam boards use different values of $g$ in their calculations. Use our exam board specific revision notes to find out which value your exam board uses.

Explore IGCSE Physics Revision Resources

Sign up for articles sent directly to your inbox

Receive news, articles and guides directly from our team of experts.

Share this article

Author

Reviewer

Author: Ann Howell

Expertise: Physics Content Creator

Ann obtained her Maths and Physics degree from the University of Bath before completing her PGCE in Science and Maths teaching. She spent ten years teaching Maths and Physics to wonderful students from all around the world whilst living in China, Ethiopia and Nepal. Now based in beautiful Devon she is thrilled to be creating awesome Physics resources to make Physics more accessible and understandable for all students, no matter their schooling or background.

Author: Dan Mitchell-Garnett

Expertise: Physics Content Creator

Dan graduated with a First-class Masters degree in Physics at Durham University, specialising in cell membrane biophysics. After being awarded an Institute of Physics Teacher Training Scholarship, Dan taught physics in secondary schools in the North of England before moving to Save My Exams. Here, he carries on his passion for writing challenging physics questions and helping young people learn to love physics.

The examiner written revision resources that improve your grades 2x.

Join now