Newton’s Third Law of Motion – Lesson Summary

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Learning Objective

In this lesson we will learn about Newton’s third law of motion.

Learning Outcomes

By the end of this lesson you will be able to:

  • State Newton’s third law of motion.
  • Describe how Newton’s third law applies to stationary objects and moving objects, with examples.
  • Identify the action force and reaction force in an action-reaction force pair.
  • Define ‘thrust’ and explain how it can be used to move objects, with examples.

 
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Lesson Topics

1 | Newton’s Third Law

2 | Examples of Newton’s Third Law

3 | Thrust

4 | Summary

Lesson Summary

  • Newton’s third law of motion states that for every action, there is an equal and opposite reaction.
  • In other words, every action force results in a reaction force that is equal in magnitude and opposite in direction.
  • These two interacting forces are known as an action-reaction force pair.
  • Thrust is a type of reaction force that enables the propulsion of objects such as boats, planes and rockets.
  • Thrust is generated when a mass of gas or liquid is accelerated in one direction by a device such as a propeller, jet engine or rocket engine, creating a reaction force in the opposite direction.

 
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