Newton” s Laws of motion:
A famous scientist Isaac Newton presented 3 laws about motion which are known as Newton” s laws of motion.
Newton” s first law of motion:
Some bodies around us are in motion, some are in uniform motion and some are at rest. Newton” s first law deals with uniform motion and bodies at rest.It is also called Law of Inertia.
“A body at rest will remain at rest and a body in motion will continue its motion with uniform speed in straight line unless a net force acts upon it.”
According to this law when net force acting on a body is zero weather it is in motion or rest acceleration produced in the body will be zero.
Mathematically When F=0, a=0 There are two parts of this law. The first part of the law is for the bodies at rest while the second part is for the bodies in motion.
According to first part a body at rest will remain at rest unless no net force acts upon it. When the net force act upon body changes or tends to change state of rest. For example a chair lying in the room will remain stationary in the room and will not change state of rest unless some one moves it by applying met force on it.
According to the 2nd part of this law a body in motion will continue its motion in straight line with uniform speed in the absence of net force. But if net force acts on body in motion it will change the uniform motion of the body either changing direction or changing speed.
For example if we through a ball it must continue its uniform motion in straight line unless net force acts upon it. But it is in our common observation that ball stops after some time by covering some distance. Why ball stops? It stops because there are forces acting on the moving ball like force of Gravity, Friction force, Air resistance. If these forces are removed then ball will continue its motion in straight line. Hence ball stops but obeys Newton” s first law of motion.
This law is also known as Law of Inertia.About Inertia I shall write in my next blog.