Name the physical quantity whose $SI$ unit is "newton".

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

Name the $CGS$ unit of force. How is it related to Newton?

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

Explain the following:
$(i)$ Why do we jerk wet clothes before spreading them on a line?
$(ii)$ Why does dust fly off when a carpet is hit with a stick?
$(iii)$ Why do fruits fall off the branches in a strong wind?
$(iv)$ Why does a pillion rider fall forward when the driver of a two-wheeler suddenly applies brakes?

$(a)$ State Newton's first and third laws of motion.
$(b)$ $A$ car of mass $1800 \, kg$ moving with a speed of $10 \, m s^{-1}$ is brought to rest after covering a distance of $50 \, m$. Calculate the force acting on the car.