Mountain roads rarely go straight up but wind up gradually. Why?

Two balls $A$ and $B$ of masses $m$ and $2m$ are in motion with velocities $2V$ and $V$ respectively. Compare:
$(i)$ their inertia,
$(ii)$ their momentum,and
$(iii)$ the force needed to stop them in the same time.

$(a)$ State Newton's second law of motion. Use this law to find a method to measure force acting on an object.
$(b)$ From a rifle of mass $4 \ kg$,a bullet of mass $50 \ g$ is fired horizontally with an initial velocity of $40 \ m \ s^{-1}$. Calculate the initial recoil velocity of the rifle.

$A$ truck starts from rest and rolls down a hill with constant acceleration. It travels a distance of $400 \, m$ in $20 \, s$. Find its acceleration. Find the force acting on it, if its mass is $7$ metric tons.

$(a)$ Why are the wheels of vehicles provided with mudguards?
$(b)$ $A$ cricket player lowers his hands while catching a ball. Why?
$(c)$ Why is a glass pane of a window shattered when a flying pebble hits it?

$A$ large truck and a mini bus both moving with a velocity of magnitude $V$ have a head-on collision and both of them come to a halt after that. If the collision lasts for $1 \, s$:
$(a)$ Which vehicle experiences the greater force of impact?
$(b)$ Which vehicle experiences the greater change in momentum?
$(c)$ Which vehicle experiences the greater acceleration?