What is the importance of Newton's laws of motion?

Newton's First Law of Motion

Everybody remains in a state of rest or of uniform motion along a straight line unless it is acted upon by an external force.

Thus from the above statement acceleration is zero if and only if the net force acting on the body is zero if  a=0.

This law states that everybody resists the change in its state of rest or that of uniform motion This property is known as inertia. Thus Newton's first law is also called the law of inertia. If no force acts on a body, there always exists a reference frame in which the body has no acceleration. Such a reference frame is called an inertial reference frame,

Newton's Second Law of Motion

The rate of change of linear momentum is directly proportional to the net force acting on the body and takes place in the direction of the force.

Newton's Third Law of Motion

For every action, there is an equal and opposite reaction Of a body. A exerts a force F on body B. then B exerts a force -F on A

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