The $SI$ unit of force is

$A$ block is supported by a cord $A$ from a rigid support,and another cord $B$ is attached to the bottom of the block. If you give a sudden jerk to $B$,it will break. But if you pull on $B$ steadily,$A$ will break. Why?

What would happen if a fielder stops a fast-moving ball suddenly? Justify your answer.

$A$ large truck and a car,both moving with speed $v$,have a head-on collision and both of them come to a halt after that. If the collision lasts for $10 \ s$:
$(i)$ Which vehicle experiences the greater force of impact?
$(ii)$ Which vehicle experiences the greater momentum change?
$(iii)$ Which vehicle experiences the greater acceleration?
$(iv)$ Why is the car likely to suffer more damage than the truck?

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

Name the physical quantity that measures inertia. State its $SI$ unit.