Question

what is inetia of an object
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Answer 1

An object continues its state of rest unless any external force acting on it is known as inertia of an object

Answer 2

Inertia:

the resistance an object has to a change in its state of motion. Newton's conception of inertia stood in direct opposition to more popular conceptions about motion. The dominant thought prior to Newton's day was that it was the natural tendency of objects to come to a rest position.