$A$ water tanker filled up to $2/3$ of its height is moving with a uniform speed. On sudden application of the brake,the water in the tank would

State Newton's first law of motion.

The action-reaction forces:

$(a)$ 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?

$A$ 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

An athlete runs some distance before taking a long jump,because