NEWTON'S LAWS

THE FIRST LAW


Newton's First  Law says that an object will continue in its state of motion unless compelled to change by a force impressed upon it. If the object is at rest, then it will stay at rest, and if it is moving, then it will continue to move at a constant speed in a straight line.
            Basically, no force means no change in velocity. This property of objects, their natural resistance to changes in their state of motion, is called Inertia. In fact, the First Law is often referred to as the Law of Inertia.


THE SECOND LAW


Newton's second Law predicts what will happen when a force does act on an object: The object's velocity will change; the object will accelerate. More precisely, it says that its acceleration (a), will be directly proportional to the magnitude of the total-or net-force(F) and inversely proportional to the object's mass(m):


                                      F = ma
  This is the most important equation in mechanics!
  
THE THIRD LAW


This is the law that's commonly remembered as, to every action, there is an equal, but opposite, reaction. More precisely, if object 1 exerts a force on object2, then object 2 exerts a force back on object 1, equal in strength but in the opposite direction. These two forces, F(1-on-2) and  F(2-on-1), are called an action/reaction pair.