When balanced forces act on a body,the body is

$(a)$ State Newton's second law of motion. Express it mathematically and find the $SI$ unit of force from it.
$(b)$ In the diagram given below, if the card is flicked away with a jerk, what will you observe? Explain the reason for this observation.

$(a)$ Define momentum. Write its $SI$ unit.
$(b)$ $A$ car and a truck have the same momentum. Whose velocity is more and why?
$(c)$ $A$ bullet of mass $20 \ g$ moving with a speed of $500 \ m s^{-1}$ strikes a wooden block of mass $1 \ kg$ and gets embedded in it. Find the speed with which the block moves along with the bullet.

State whether the following statement is true or false:
In any interaction,there are always at least two forces in play.

The inertia of an object tends to cause the object

Given below are some measuring units of different physical quantities:
$kg\, ms^{-2}, ms^{-2}, kg\, ms^{-1}, ms^{-1}, kg\, m^2 s^{-2}$
Select the units which measure force and momentum respectively.