Action and Reaction Pair in Nature

There are various examples around us that supports the law of action and reaction and they are added below,

Swimming of a Fish:

A fish uses its fins to push water backward to simulate its motion. In turn, the water exerts an equal reacting force by pushing the fish forward, propelling the fish through the water.

The magnitude of the force exerted by the fish on the water is equivalent to the size of the force on the fish. The direction of the force on the water which is backward in nature is opposite the direction of the forward force on the fish.

Flying of Birds in Air:

The flying motion of birds is governed by the birds pushing down on the air with their wings, while the air in return pushes their wings up and gives them lift. The direction of the force on the air which is backward in nature is opposite the direction of the forward force on the birds. Action-reaction force pairs make it possible for birds to fly.

Proof that Action and Reaction are Equal and Opposite

To understand the concept of the action and reaction forces, let us consider a system of two spring balances A and B connected together. 

The spring balance B is fixed to any rigid support. A force is then applied in the loose and free end, by pulling the spring balance A. As an effect of the application of force, both the spring balances show the same readings. 

This concludes that both the spring balances witness equal magnitude forces. It also shows that the force exerted by both the spring balances, A on B is equal but opposite in direction to the force exerted by spring balance B on A. 

Here, he force exerted on the acting body (the spring balance A on B) is termed as action, and the force exerted by the reacting body (spring balance B on A) can be termed as reaction.

Law of Action and Reaction is the other name for Newton’s Third Law of Motion. There are three basic laws given by famous English Physicist Isaac Newton that are helpful in defining the motion of any object in an inertial frame of reference. The third law of Newton is also called the Law of Action and Reaction. As its name suggests, it explains, “For any action to an object, we have an equal and opposite reaction.”

This could be explained by the example that if we have a ball that strikes a wall with a force of F₁ (action force), and the wall applies a force of F₂ (reaction force), then the action force is always equal to the reaction force, i.e. F₁ = F₂

In this article, we will learn about Newton’s Third Law of Motion (Law of Action and Reaction), its Examples, and others in detail.