The inertia of an object tends to cause the object

Identify the type of inertia experienced by the brain,when
$(a)$ the head is hit suddenly with a stick.
$(b)$ a car is suddenly made to stop using brakes.
$(c)$ a boxer punches another boxer in the face.

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

$A$ bullet of mass $5 \, g$ travelling at a speed of $120 \, m s^{-1}$ penetrates deeply into a fixed target and is brought to rest in $0.01 \, s$. Calculate: $(a)$ the distance of penetration in the target,$(b)$ the average force exerted on the bullet.

Which Newton's law of motion is applied in the flight of a bird?

Explain the following:
$(i)$ Why is it difficult to walk on marshy land?
$(ii)$ Why does an air-filled balloon rise up slightly when punctured from below?
$(iii)$ Why does a swimmer push water backward with his hands in order to swim in the forward direction?