Definition of momentum\\
It is convenient to define a physical quantity called momentum, usually indicated by the symbol , as the product of its mass by its velocity
The momentum is a vector quantity which has the same direction as the velocity of a body.
The unit of measurement of momentum in the SI system is the product of the units of mass and velocity and thus is the kg m/s.
A new form of the Second Newton’s Law\
Newton’s Second Law can be expressed in terms of change in momentum:
(2)which can be written in the more compact form