# What are some examples of Newton's third (3rd) law?

• accelerate23
In summary, Newton's third law states that for every action, there is an equal and opposite reaction. This means that when an object exerts a force on another object, the second object exerts an equal force in the opposite direction. This is demonstrated in various scenarios, such as a ball hanging from a string, a person kicking a ball, and even in everyday actions like pressing a key on a keyboard or walking. It is important to note that the action and reaction forces always act on different objects.
accelerate23
If you want, could you give me at least 5 so that I can fully understand.

http://en.wikipedia.org/wiki/Newton_third_law

A ball hang by a string which attached to a ceiling.
The ball pull the string down, the string pull the ball up.
The string pull the ceiling down, the ceiling pull the string up

Newtons third law states that if an object A applies a force on object B (called action)

Object B applies an equal and oppsite force on object A (called reaction).

REMEMBER: Action and Reaction forces always act on different object.

IF ACTION ACTS ON B , then REACTION ACTS ON A.

Eg 1

The Earth pulls you by force mg towards it, you pull the Earth towards yourself with reaction force whose value is also mg.

Eg 2:
Cristiano Ronaldo applies a force on ball to kick it, the ball applies the same force on Ronaldo which is the reaction.

Eg 3:

When i pressed the key 3 on my keyboard with a force, the key pushed back on me with a reaction force.

Eg 4: this is an imp one.

a book rests on a table.
The Earth is pulling it down with force mg.
However, the table is applying an opposing force F which balances mg to keep the book at rest.

HOWEVER, THE FORCE F IS NOT THE REACTION FORCE TO mg.

remember, action and reaction always act on different objects.

Here both F and mg both act on A so they can't be action reaction pair.

In fact, The reaction force of mg on book by earth, is actually acting on earth.

The reaction of force F on book by table acts on table.

In this particular case F=mg which is why the book is at rest, but they are not action reaction forces.

Eg 5: Another imp one.

While walking we apply a force on Earth in backward direction with our feet.
Its reaction acts on us and pushes us forward making us walk.

Hope this helps.

Last edited:

Newton's third law, also known as the law of action and reaction, states that for every action, there is an equal and opposite reaction. This means that when one object exerts a force on another object, the second object will exert an equal and opposite force back.

1. When you push against a wall, the wall pushes back against you with an equal force. This is why you cannot walk through a wall.

2. When a rocket is launched into space, the force of the rocket's engines pushing down on the ground creates an equal and opposite force that propels the rocket upwards.

3. When a person jumps off a diving board, the force of their feet pushing down on the board creates an equal and opposite force that propels them upwards into the air.

4. When a balloon is inflated, the air molecules inside push outwards against the walls of the balloon. In response, the balloon exerts an equal and opposite force inwards, keeping the air molecules contained.

5. When a person is rowing a boat, the force of the oar pushing against the water creates an equal and opposite force that propels the boat forward.

## 1. What is Newton's third law?

Newton's third law states that for every action, there is an equal and opposite reaction. This means that when two objects interact, the force exerted by one object on the other is equal in magnitude and opposite in direction to the force exerted by the second object on the first.

## 2. Can you give an example of Newton's third law?

A common example of Newton's third law is the recoil of a gun. When a bullet is fired from a gun, the gun experiences a recoil force in the opposite direction. This is because the bullet exerts a force on the gun, and according to Newton's third law, the gun exerts an equal and opposite force on the bullet.

## 3. How does Newton's third law relate to everyday life?

Newtons's third law can be seen in many everyday situations, such as walking, swimming, and even sitting in a chair. When we walk, our feet push against the ground, and the ground pushes back with an equal and opposite force, propelling us forward. When we swim, we push against the water, and the water pushes back, allowing us to move through it. Even when we sit, our weight pushes down on the chair, and the chair pushes back up with an equal force, keeping us from falling through.

## 4. Does Newton's third law apply to all types of forces?

Yes, Newton's third law applies to all types of forces, including gravitational, electromagnetic, and contact forces. For example, when you push a door to open it, your hand exerts a force on the door, and the door exerts an equal and opposite force on your hand.

## 5. Why is Newton's third law important in physics?

Newton's third law is important in physics because it helps us understand the relationship between forces and motion. It explains why objects move and accelerate in certain ways and allows us to predict the motion of objects based on the forces acting on them. Additionally, Newton's third law is the basis for many engineering and technological advancements, such as rockets and airplanes.

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