Newton’s First Law Of Motion
INERTIA: Inertia is the property of a body by which unable to change it’s state by it’s own mass is measure of inertia force is that which changes or tends to change the state of a body inertia means resistance to change state.
The inability to change the state of rest of a body by itself is known as inertia of rest.
The inability to change the state of motion of a body by itself is known as inertia of motion.
The inability to change the state of direction of a body by itself is known as inertia of direction.
Following examples from our daily life illustrate the law of inertia:
1.When a running horse suddenly stops,the rider falls forwards.Because the lower part of the body of the rider (which is in contact with the horse)comes to rest;but because of inertia,the upper part of the body tends to keep on moving.As a result of it,the rider falls forwards.
2.When a horse suddenly starts moving,the rider falls backwards.Because the lower part of the body of the rider (which is in contact with the horse)comes in motion;but becuase of inertia ,the upper part tends to be at rest.Hence,the rider falls backwards.
3.We hit a carpet with a stick remove the dust.On hitting with a stick,the carpet comes into motion;but because of inertia ,the dust particles remain at rest.Due to this,dust particles get removed from the carpet.
4.If a cloth placed under a book is given a sudden pull,it goes out without disturbing the book.Because the book continues to be at rest due to inertia,when the cloth is suddenly pulled out.
5.The sparks coming out of a griding stone are tangential to the rotating stone.It is due to directional inertia .Once the sparks are produced,no external force acts on the sparks and in the absence of external force,their direction of motion cannot change.The sparks so produced follow paths tangential to the griding stone.
6.The mud from the wheels of a moving vehicle flies off tangentially.It also happens for the reasons explained above.In order that the flying mud does not spoil the clothes of the passersbyes,the wheels are provided mudguards.