FIRST LAW OF MOTION OR LAW OF INERTIA
According to first law of motion an object at rest will remain at rest or an object in motion will remain at motion at constant velocity unless acted upon by a force.
It also gives the idea that to change the state of rest or uniform motion of a body in a straight line some external agency is needed. This agency is called force.
Example:
a. A moving football slows down and then stops often sometime. It comes to rest due to the friction between the ground and the ball.
b. To take start in sprint races, to lift the opponent in wrestling, to start hammer throw.
SECOND LAW OF MOTION (The Law of Acceleration)
According to Newton’s second law of motion, the rate of change of momentum of a body is directly proportional to the impressed force and takes place in the direction of force.
Example:
a. A cricket player while catching a ball moves his hands backwards. Initially the ball is moving with a certain velocity. The player has to apply a retarding force to bring the ballot rest in his hands.
b. In baseball player hits the ball hard to throw it far away.
THIRD LAW OF MOTION
According to the Newton’s third law of motion, to every action there is always an equal and opposite reaction.
Example:
a. The swimmer pushes the water in the backward direction with a certain force. Water pushes the man forwards with an equal and opposite force.
b. Walking: when a person walks on the road, he presses the ground in backward direction and the ground exerts an equal and opposite force on the person in the forward direction.
c. Shooting: when a bullet is fired from a rifle with a certain force (action) there is an equal and opposite force exerted on the rifle in the backward direction (reaction)
