First law of motion

Def- body at rest will remain at rest position only and a body which is in motion continues to be in motion unless otherwise they are acted upon by an external force. OR An object remains in a state of rest or of uniform motion in a straight line unless compelled to change that state by an applied force. Also known as the law of inertia. The objects which are at rest or are moving uniformly with the same velocity are to be called inertia. That means the object is at its inertia.