If one of these two forces is considered as action, then other will be reaction. (c) Law 3: When a body A exerts a force on another body B, B exerts an equal and opposite force on A. In, the quantity m is called “inertial mass” of body Where F is the resultant impressed force and a is the acceleration

Gives relation between force and acceleration (a) Law 1: Everybody remains at rest or continues to move with uniform velocity unless an external force is applied to it. It is an agent that changes or tends to change the state of rest or of uniform motion of a body in a straight line.