What is the force required to accelerate a $2 \, kg$ mass by $5 \, m s^{-2}$ (in $, N$)?

Two balls $A$ and $B$ of masses $m$ and $2m$ are in motion with velocities $2V$ and $V$ respectively. Compare:
$(i)$ their inertia,
$(ii)$ their momentum,and
$(iii)$ the force needed to stop them in the same time.

In oil tankers,some space is left at the top while filling them. Explain why.

Action-reaction forces act

Newton's first law of motion is also called the law of inertia. Why?

What is the $SI$ unit of force?