What is momentum? Write its $SI$ unit. Interpret force in terms of momentum. Represent the following graphically:
$(a)$ Momentum versus velocity when mass is fixed.
$(b)$ Momentum versus mass when velocity is constant.

(N/A) Momentum is defined as the product of the mass and velocity of an object. It is a vector quantity.
Momentum $(p)$ = mass $(m)$ $\times$ velocity $(v)$
The $SI$ unit of momentum is $kg\, m\, s^{-1}$.
Force is defined as the rate of change of momentum. According to Newton's second law of motion,the force applied on an object is directly proportional to the rate of change of its momentum.
Force $(F)$ = $\frac{\Delta p}{\Delta t}$
Graphical representation:
$(a)$ Since $p = mv$,if mass $(m)$ is fixed,momentum $(p)$ is directly proportional to velocity $(v)$. The graph of momentum versus velocity is a straight line passing through the origin.
$(b)$ Since $p = mv$,if velocity $(v)$ is constant,momentum $(p)$ is directly proportional to mass $(m)$. The graph of momentum versus mass is a straight line passing through the origin.