From a rifle of mass $4\, kg$,a bullet of mass $50\, g$ is fired with an initial velocity of $35\, m\, s^{-1}$. Calculate the initial recoil velocity (in $m/s$) of the rifle.

Explain why some of the leaves may get detached from a tree if we vigorously shake its branch.

$A$ hockey ball of mass $200 \,g$ travelling at $10 \,m \,s^{-1}$ is struck by a hockey stick so as to return it along its original path with a velocity of $5 \,m \,s^{-1}$. Calculate the magnitude of the change in momentum of the hockey ball due to the force applied by the hockey stick.

$A$ $8000 \,kg$ engine pulls a train of $5$ wagons,each of $2000 \,kg$,along a horizontal track. If the engine exerts a force of $40000 \,N$ and the track offers a friction force of $5000 \,N$,then calculate the net accelerating force (in $N$).

Akhtar, Kiran, and Rahul were riding in a motorcar that was moving with a high velocity on an expressway when an insect hit the windshield and got stuck on the windscreen. Kiran suggested that the insect suffered a greater change in momentum compared to the motorcar. Akhtar said that since the motorcar was moving with a larger velocity, it exerted a larger force on the insect. Rahul said that both the motorcar and the insect experienced the same force and the same change in momentum. Comment on these suggestions.

$A$ hammer of mass $500 \,g$,moving at $50 \,m/s$,strikes a nail. The nail stops the hammer in a very short time of $0.01 \,s$. What is the force (in $N$) of the nail on the hammer?