AQA GCSE Newton's 3rd Law(Physics)

Newton’s 3rd Law

Whenever two objects interact, they exert equal and opposite forces on each other. 

Make sure you take careful note that the force arrows are on different objects under Newton’s 3rd law. 

Under Newton’s 3rd law, these forces will always occur in pairs.

Newtons 3rd law with a box on a table

In the example above there are two forces F1 and F2.

F1 is an upward force of the table on the box. 

F2 is a downward force of the box on the table

Both forces are equal in size, opposite in direction, and act on different objects!

Another example of Newton’s 3rd law is the force of gravitational attraction between the Sun and the Earth.

Force of gravitational attraction between the Sun and the Earth to demonstrate newtons 3rd law

F1 is the Earth’s gravitational force of attraction on the Sun.

F2 is the Sun’s gravitational force of attraction on the Earth.

Both forces are equal in size, opposite in direction and are acting on different objects.

Practice Question

1.Define Newton’s Third Law 

2.Describe how Newton’s Third Law applies when a swimmer pushes off the wall of a pool.

3.Describe the interaction forces between Earth and the Moon according to Newton’s Third Law.

Accordion Content

Accordion Content