Newton’s Second Law of Motion states that when a non-zero resultant force is applied to an object it causes the object to accelerate. The resultant force is proportional to the acceleration. More precisely, the resultant force is the product of the object’s mass and its acceleration.

Newton’s Second Law of Motion:

The resultant force acting on a body is equal to its mass multiplied by its acceleration. Mathematically speaking,

${\bf F}=m{\bf a}$

Consider two objects with different masses. Object 1 has a mass much larger than object 2. From Newton’s Second Law we can see that the force required to give the objects the same acceleration will be much larger for object 1.

Newton’s Second Law is closely related to Newton’s First Law if you consider a resultant force of 0. When an object is either stationary or moving with constant velocity its acceleration is zero. It follows that the resultant force is zero (when zero acceleration is multiplied by non-zero mass). Newton’s Second Law is a more general statement about forces than Newton’s First Law.

This is the most used of Newton’s Laws and is often referred to as ‘The Law of Motion’.