explanation of law of inertia

Asked by shivesh242 | 26th Jul, 2021, 08:30: PM

Expert Answer:

Law of inertia is stated as follows
 
Every body continues to be in its state of rest or of uniform motion in a straight line unless compelled by some external force to act otherwise .
 
Let us assume a heavy mass is at rest on floor. If we try to push or pull with little amount of force  it will not move initially.
 
Though the force is applied , heavy mass is not moving means some other force acting against our applied force. 
This other force is friction force. Friction force cancel our applied force , hence due to net zero force , heavy mass is not moving.
 
When we put more effort to push or pull the heavy mass, it starts moving becuase our applied force is greater than friction force
and there is a net non-zero force acting on heavy mass . Hence the heavy mass is moving.
 
Hence from the law of inertia, heavy mass on floor continues to be in its state of rest  unless compelled by some net external force to act otherwise
 
Let us assume a car is moving with uniform speed. Let the engine be switched off .
On a smooth road , the car will keep on moving with same speed for ever.
 
But on a rough road, the car will come to stop after moving some distance that depends how rough road it is .
Again this is due to friction force.
 
On smooth road , the car goes on moving uniform speed because friction force is absent or negligible.
On a rough road, the car comes to rest becuase significant friction force opposing the motion of car.
 
Hence from the law of inertia, the moving car continues to be in its state of uniform motion in a straight line unless compelled by
some external friction force to act otherwise .

Answered by Thiyagarajan K | 26th Jul, 2021, 11:38: PM