# Newton’s third law

Galileo , through his speeches and mathematical demonstrations, had managed to explain the movement that was involved in the fall of the bodies and the trajectory of the projectiles. Putting aside Aristotle’s speculations on motion, he founded kinematics on scientific and experimental bases , that is, the part of mechanics that describes the motion of bodies regardless of the forces that produce it. From these studies, Newton managed to develop dynamics , a science that studied the relationships that occurred between theforces and the movements that they originate. In the second section of the Mathematical Principles of Natural Philosophy, Newton established the three “axioms or laws of motion .

## What is Newton’s third law?

The Newton ‘s third law tells us that the interactions that occur between two bodies are always equal but will be directed in direction opposite to the first body that for every action there is a reaction .

• What is Newton’s third law?
• Who proposed it
• History
• Statement
• Characteristics of Newton’s third law
• Formula
• Target
• Explanation
• Applications of Newton’s third law
• Experiment
• Examples
• Conclution

## What is Newton’s third law?

The law is that when an object displays a force on another object , the second object exerts a force of equal magnitude and direction opposite the first. When any type of interaction occurs, there is also a pair of action and reaction forces , whose magnitude is equal and the directions are opposite. These forces occur in pairs, so the pair of action and reaction forces form an interaction between two objects.

Newton’s third law is also known as the action and reaction principle .

## Who proposed it

Newton’s third law is completely unique to Isaac Newton . Let us remember that the other two laws already had an elaborate scientific basis for Galileo, Hooke and Huygens.

## History

The Third Law as its name implies was created by Isaac Newton , when he began to wonder why objects were moving . The story of the third law is based on an apple, and how the scientist inspired his knowledge from the fall of an apple from a tree.

## Statement

The original statement of the law says the following:

“Action is always opposed an equal reaction: or the mutual actions of two bodies are always equal, and directed opposing parties.”

In Spanish, this statement says the following: with every action an equal and opposite reaction always occurs : it means that the mutual actions of two bodies are always equal and directed in the opposite direction.

## Characteristics of Newton’s third law

The main characteristics of Newton’s third law are as follows:

• It is an original law formulated by Isaac Newton .
• One object exerts a force on a second object
• Forces never occur individually , but rather in equal and opposite pairs.
• It is only possible to work in a vector way, since like any vector it has magnitude , direction and meaning .
• The action and reaction force act at the same time with the same magnitude and direction but in the opposite direction.
• The direction is given by the angle of inclination of both forces.

## Formula

Mathematically, the third law of motion of Newton can be expressed by the following formula:  F1 = F2 ‘Where F1 is the force that acts on the body 1 and F2′ force reactive acting on the body 2.

## Target

The main objective of Newton’s third law is to identify the types of forces involved in the motion of objects. He also made great contributions to classical mechanics as it is a system that explains how force is related to the movement of bodies.

## Explanation

This law explains the forces of action and reaction, which are forces that can be exerted by all bodies that come into contact with another. These forces are equal but at the same time they are opposite in the aspect of the direction . Every time one body exerts force on another, the latter also exerts force on the first object.

In Newton’s third law, what we know as the action force intervenes and this force is the one that is exerted by the first body that makes force on the other, and the reaction force also intervenes , which is the one possessed by the body that receives and reacts .

## Applications of Newton’s third law

Some of the applications in which we can observe the third law are the following:

• Row in boats.
• Takeoffs rockets .
• A being in position of standing on the ground.
• In gun shots .
• It is also used in structures and buildings .
• Satellite repair .

## Experiment

#### The Reactive Balloon

• Materials:  a balloon , string , tape , and an L-shaped straw .
• Procedure:  first we must inflate the balloon, then we put the folded straw in the mouth of the balloon and it is fixed with adhesive tape. On the line of the largest diameter of the balloon, we glue the end of the thread and hold the other end of the thread at a certain height . Hold the balloon and you will see the balloon spin as it deflates.

## Examples

Some examples of Newton’s third law are:

• When we swim in a pool because when we look for the wall and push ourselves to get momentum we can detect an action and a reaction .
• When a nail is hammered into a surface, the hammer makes a backward motion, which is identified as the reaction to its own blow .
• When a person pushes another with a similar body . In this case, the person will not only go back but also the one who pushed him.
• When you are rowing a boat because while move the water to back with the paddle, it reacts pushing the boat in its opposite direction .

## Conclution

Newton’s third law explains the forces of action and reaction and teaches us that they are forces that we can find in all bodies when they are in contact with each other, that they are equal but at the same time are opposite ; they have the same module and sense , but in  direction they are opposite . By this we mean that one body exerts a force on another but that this other also exerts a force on it.

We know by the name of action force the force that is exerted by the first body and therefore, we call the reaction force that which is originated by the body that receives and reacts to the force.