$100$ balls each of mass $m$ moving with speed $v$ simultaneously strike a wall normally and reflect back with the same speed in time $t \ s$. The total magnitude of force exerted by the balls on the wall is

$A$ force-time $(F-t)$ graph for a linear motion is shown in the following figure. The segments shown are circular. The linear momentum gained between $0$ and $8 \,s$ is

Which force acts on a body first: action or reaction?

$A$ batsman hits a ball of mass $0.2 \ kg$ straight towards the bowler without changing its initial speed of $6 \ m/s$. What is the impulse imparted to the ball (in $Ns$)?

$A$ bob of mass $10m$ is suspended through an inextensible string of length $l$. When the bob is at rest at the equilibrium position, two particles of mass $m$ each, moving with velocity $u$, strike the bob at an angle of $60^{\circ}$ with the string and get simultaneously attached to it. What is the value of the impulsive tension $J$ in the string during the impact?

$A$ $150\, g$ tennis ball coming at a speed of $40\, m/s$ is hit straight back by a bat to a speed of $60\, m/s$. The magnitude of the average force $F$ on the ball,when it is in contact for $5\, ms$,is ........... $N$.