Newton's law of motion is threefold. 1. Unless applied by force exerted on an object from the outside , the stationary object will remain stationary forever and the moving object will always move in a straight line or in a straight path with constant velocity. 2. The rate of change of momentum of an object is proportional to the applied ball and the change of momentum of the object occurs in the direction in which the force acts. 3. Every action has an equal and opposite reaction