As per Newton's third law of Motion
When one object exerts a force on other object
The other object also exerts an equal and opposite force on the first object
In easy language
Every action has an equal and opposite reaction
Example 1
Walking
When we walk,our feet exert a force on ground in backward direction
The ground exert a force in forward direction
This makes us move forward
Example 2
Jumping to Land from Boat
When a sailor jumps back from boat,it exerts a pressure on boat backwards
The boat exerts equal force on sailor in forward direction
This makes person get out of board
Example 3
Slapping
When teacher slaps a student hard
This hurts students face as well as teacher's hand
Hand of teacher exert a force on students palm
Student's palm exert equal force on students hand
Example 4
Colliding of 2 footballers
If 2 footballers A and B collide, both of them are hurt
This is because force is exerted by both A and B on each other
Example 5
Recoil of Gun
When a gun is fired,
It exert forward force on bullet
Bullet also exert equal and opposite force on gun
This is called recoil of gun
Important Points of Third Law of Motion
There are 2 forces - one force is called action and the other force is called reaction
Both force act in opposite direction
Both forces occur on different bodies
Both forces are equal
However, Acceleration produced may be different because of different mass of 2 bodies
(Force = Mass x Acceleration)
Explanation
As per Newton's third law of Motion
Force of One body = Force of Other Body
Mass of First body x Acceleration of first body = Mass of Second Body x Acceleration of Second body
It can be seen that
If mass of first body is more than second body
then Acceleration of first body will be less than Acceleration of Second body
Example
A small boy of mass 40 kg collides with man with mass of 80 Kg
On Collision,boy will exert force on man
Man will exert equal and opposite force on boy
But since boy has less mass than man
Boy will feel more pain as acceleration produced in boy wil be more
Explanation
Suppose boy has mass of 40 kg and it collide with man(80 kg) with acceleration of 3 m/sec
Force Produced by Boy=40*3=120 kg m/s
As per Newton's Third Law of Motion ,Force Produced by Man =Force produced by boy
Force Produced by Man=120 kg m/s
Mass*Acceleration=120 kg m/s
80*Acceleration=120
Acceleration=120/80=1.5 m/sec
Hence Acceleration produced in man (1.5m/sec) will be much less than boy (3 m/sec)
