Newton’s Third Law of Motion: Examples - Embibe
• Written By Rumela_M
• Written By Rumela_M

# Newton’s Third Law of Motion

You might be aware that we exert a gravitational pull towards the earth. This means that the Earth pulls us down. But do you know, that we exert an opposite force on the Earth because of which it tends to be pulled up? Let’s see another instance. When we throw a ball against the wall it bounces back. This happens in a fraction of a moment but let us understand what actually takes place here. When we throw a ball against a wall, the ball exerts a force on the wall first. Equally, the wall exerts a force on the ball resulting it to bounce back from the wall and return to us. This is explained by Newton’s Third Law of Motion.

## Explaining Newton’s Third Law of Motion

When two objects interact, the interaction results in a push or a pull acting upon the object. This push or pull that takes place as a result of the interaction of the two objects, is called force

Newton’s third law of motion action states that every action has an equal and opposite reaction. This means that if two objects come in contact, and the first object exerts a force on the second object, the second object must also exert a force of an equal magnitude on the first object, in the opposite direction.

Thus we can observe that Newton’s third law of motion represents two things:

• A certain symmetry in nature
• Forces always occur in pairs. In simpler words, it means that If one body has to exert a force on another, it will also experience a force on itself.

### Applications of Newton’s Third Law of Motion

We can explore three types of forces using Newton’s third law of motion, namely, normal force, tension and thrust, respectively. Let us see how Newton’s third law of motion applies on each of them:

• Normal Force = Gravitational force acts on all objects that are present in the earth. However, not all the objects fall freely in the same state towards the centre of the earth. This happens because of normal force. Normal force works perpendicular to the surface on which the object is placed. It is a force that a surface applies to an object in order to support its weight. If an object lying on a flat surface does not accelerate, the net external force on it is zero. It is represented by the formula:

N = mg.

• Tension = Tension, meaning “stretch” in Latin, is there force that acts along the length of a flexible connector, such as a string, rope, chain, or cable. It is a pull that acts parallel to the connector and acts in the opposite direction at the two ends of a connector.
• Thrust = When rockets move upwards, they push back gases at high velocity with a lot of force. This reaction force is called thrust.

### Examples of Newton’s Third Law of Motion

Here are some examples from our everyday life occurrences that will help you to understand how Newton’s third law of motion functions:

• Fishes use their fins to push water backwards. This helps them to accelerate the water and move forward.
• The above principle is used by human beings to swim in the water.
• Acceleration in a car happens as a result of the ground question forward on the drive wheels while the drive wheels push backwards on the ground.
• Helicopters push down the air and lift themselves up. This creates an upward reaction force in helicopters. Just the way in which a fish uses its fins to push back water and swim forward, in a similar manner, a bird uses its wings to bring down wind and fly upwards into the sky.
• During the firing of a gun, the bullets accelerate forward with force. At the same time, the gun recoils back with force.
• To climb up, the rock climbers have to pull the vertical ropes in the downward direction.
• Air is deflected to one side of a spinning ball as it moves in the opposite direction.
• Rockets and jet engines produce thrust and hot exhaust gases from the back of their engines and a thrusting force is produced in the opposite direction as they move upwards.

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