When a $4 \,kg$ rifle is fired,the $10 \,g$ bullet receives an acceleration of $3 \times 10^6 \,cm/s^2$. The magnitude of the force acting on the rifle (in newton) is ............

$A$ machine gun fires a bullet of mass $35 \ g$ with a speed of $600 \ m/s$. The person holding the gun can exert a maximum force of $147 \ N$ on it. The number of bullets that can be fired from the gun per second is

$A$ particle is acted upon by a force whose components' variations with time are shown in the diagrams. The magnitude of the change in momentum of the particle in $0.1\,s$ is:

$A$ ball of mass $400\, g$ is dropped from a height of $5\, m$. $A$ boy standing on the ground hits the ball vertically upwards with a bat with an average force of $100\, N$ so that it reaches a height of $20\, m$. For how long does the ball remain in contact with the bat (in $, s$)? $[g = 10\, m/s^2]$

$A$ $40 \ g$ ball dropped from a certain height bounces back from the horizontal ground without losing mechanical energy. If its speed is $10 \ m/s$ just before making contact with the ground,and the average value of the force of the ground on the ball is $16 \ N$ while the ball and ground are in contact,how long were they in contact in milliseconds $(ms)$?

$A$ particle of mass $m$ is moving with a uniform velocity $v_1$. It is given an impulse such that its velocity becomes $v_2$. The impulse is equal to