Explanation of Newton’s Third Law of Motion
In both examples listed above, we can see that there are two forces that are acting on each body. In the first example, the force exerted by our feet on the ground is the action force and in response to that, the ground exerts an equal opposite force on our feet. In the second example, the force exerted by the weight of the book is the action force and the force exerted by the table on the book is the reaction force.
Action and Reaction Force
Now, let’s learn about two terms called Action and Reaction force, which are used in Newton’s third law of motion.
Action Force: The initial outside force exerted on the body is called the action force.
Reaction Force: The force the body exerts to respond to the active force in the opposite direction is called reaction force.
From the above case, Newton’s third law of motion can also be stated as:
If there is any interaction between two bodies (A and B), the force FAB (force applied by body B on body A) is equal to force FBA (force applied by body A on body B) but they are opposite in direction.
Note on Action and Reaction Forces
- Action and Reaction forces are exerted by different bodies and not by the same body.
- Action and Reaction always occur simultaneously, and they are always in pair.
Difference between Action and Reaction Force
Differences between action force and reaction force can easily be understood by the examples of action-reaction pairs as discussed below in the table.
|
Action Force |
Reaction Force |
|---|---|
| Weight of the book lying on a table acting in the downward direction is action force. | Force exerted by the table on the book in an upward direction is the reaction force. |
| Force exerted by the rocket on the burnt gases in the downward direction is action force. | Force exerted by the gases on the rocket in an upward direction is the reaction force. |
| Force exerted by the gun on the bullet in the forward direction is action force. | Force exerted by the bullet on the gun in the backward direction is the reaction force. |
Also Check, Law of Action and Reaction
Newton’s Third Law of Motion
Newton’s Third Law of Motion states that a given pair of bodies every action has equal and opposite reaction. Newton’s Third Law of Motion is one of the basic laws of physics and is very useful in various aspects. Newton’s Third Law represents a specific symmetry in the nature of forces and explains how they always exist in pairs, and one body cannot exert a force on another without also experiencing a force.
It is one of three laws of motion given by Sir Isaac Newton. Newton’s third law of motion highlights a fundamental principle of symmetry in nature. It tells us that forces are always part of a mutual exchange: when one body exerts a force on another, it inevitably experiences an equal and opposite force in return. In simpler terms, you can’t push or pull something without that something pushing or pulling back on you with the same strength but in the opposite direction.
In this article, we will learn about Newton’s third law of motion, its definition, formula, derivation, and examples of third law of motion.
Table of Content
- What is Newton’s Third Law of Motion
- Explanation of Newton’s Third Law of Motion
- Newton’s Third Law of Motion Formula
- Examples of Action-Reaction Forces
- Newton’s Third Law of Motion Examples
- Applications of Newton’s Third Law of Motion