Question

What is the law of motion?

Answer 1

Hint: Human beings have always observed that if you have an object that is moving, then it seems to stop on its own and come to rest even if we do nothing to that moving object. So, if you want to keep an object moving you have to keep applying force to it. However, some laws govern the motion of any object which we shall now analyze.

Complete answer:
For more than 2000 years, the Greeks assumed that “objects have a natural tendency to stop”. But in the 1600s, three gentlemen, Galileo, Newton and Rene Descartes described motion in a different way altogether. Newton, however, encapsulated into a broader framework with his Laws of Motion, Laws of Gravitation and other laws which were really the basis of classical mechanics.
Therefore, the Laws of Motion by Newton are as follows:
Law One: Law of Inertia
A moving object continues to stay in motion with the same speed and acceleration in the same direction and an object at rest continues to stay in its state of rest by virtue of its inertia until an external unbalanced force acts on it.
Law Two: Law of force and acceleration
Force is equal to change in momentum per unit time. Thus, the acceleration of a body in motion is given as the net force acting on the body divided by its mass.
Law Three: Law of Action and Reaction
It states that for every action (force), there is an equal and opposite reaction

Note:
The theory of relativity denies the presence of any such thing as an immovable object. Now according to Newton’s second law of motion, an immovable object must be one whose acceleration is zero which is very possible when the mass of the object is so huge that it tends to infinity. Hence, if we accelerate relative to the object with zero acceleration, we will not interpret that object as immovable.