Question

can anyone plssss tell the answer for the (a) in Question 2 in the pic (It's a physics question)

Answer 1

This happens due to the 3rd law of motion.Every action has its equal and opposite reaction.

Answer 2

The inertia of the bodies is 'm' and '5m' itself since mass is the measure of inertia. Their momenta are '5mv' and '5mv' since p(momentum) =m(mass) * v(velocity).