Newton’s First Law of Motion states that a body continue to be in its state of rest or of uniform motion along a straight line, unless it is acted upon by some external force to change the state
(1) If no net force acts on a body, then the velocity of the body cannot change i.e. the body cannot accelerate.
(2) Newton‟s first law defines inertia and is rightly called the law of inertia. Inertia are of three types :Inertia of rest, Inertia of motion, Inertia of direction
(3) Inertia of rest : It is the inability of a body to change by itself, its state of rest. This means a body atrest remains at rest and cannot start moving by its own.