**Newton's second law: Law of Motion**

The rate of change of momentum of a body is equal to the resultant force acting on the body and is in the same direction.

Newton's second law as originally stated in terms of momentum

**p**

“An applied force is equal to the rate of change of momentum”.

The physical meaning of this equation is simply a mathematical definition of a force (rate of change of momentum is called a force).

whereWhen the mass

Fis the force

pis the momentum

tis the time

vis the velocity

mis the mass

a= is the acceleration.

**m**, of the object is constant, the mathematical result of differentiation of momentum becomes simply:

If the mass m is measured in kilograms and the acceleration

**a**is measured in meters per second squared, then the unit of force is kilogram × meter/second squared. This unit is called the Newton: 1 N = 1 kg x 1 m/s².

**Newton's Second Law**