$A$ batsman hits back a ball of mass $0.4 \; kg$ straight in the direction of the bowler without changing its initial speed of $15 \; ms^{-1}$. The impulse imparted to the ball is $\dots \; Ns$.

$A$ player kicks a football of mass $0.5 \ kg$ and the football begins to move with a velocity of $10 \ m/s$. If the contact between the leg and the football lasts for $\frac{1}{50} \ s$,then the force acted on the football should be .......... $N$.

$A$ machine gun fires bullets of mass $30 \text{ g}$ with a velocity of $1000 \text{ m/s}$. The man holding the gun can exert a maximum force of $300 \text{ N}$ on it. How many bullets can he fire per second at most?

$A$ solid horizontal surface is covered with a thin layer of oil. $A$ rectangular block of mass $m = 0.4 \ kg$ is at rest on this surface. An impulse of $1.0 \ N \ s$ is applied to the block at time $t = 0$ so that it starts moving along the $x$-axis with a velocity $v(t) = v_0 e^{-t/\tau}$,where $v_0$ is a constant and $\tau = 4 \ s$. The displacement of the block,in metres,at $t = \tau$ is. . . . . . . Take $e^{-1} = 0.37$.

$A$ cricket ball of mass $250\, g$ collides with a bat with velocity $10\, m/s$ and returns with the same velocity within $0.01\, s$. The force exerted on the ball is ....... $N$.

$A$ ball of mass $60 \ g$ hits a wall with a velocity of $4 \ m/s$ and rebounds with the same velocity. The change in momentum in $kg \cdot m/s$ is: