Swimming is possible on account of

$A$ force of $50 \, dynes$ acts on a particle of mass $5 \, g$ for $3 \, seconds$. What is the impulse of the force?

$A$ ball of mass $0.15 \; kg$ hits the wall with an initial speed of $12 \; m/s$ and bounces back without changing its initial speed. If the force applied by the wall on the ball during the contact is $100 \; N$,calculate the time duration of the contact of the ball with the wall in seconds.

$A$ ping-pong ball of mass $m$ is floating in air by a jet of water emerging out of a nozzle. If the water strikes the ping-pong ball with a speed $v$ and just after collision the water falls dead,the rate of flow (in $kg/s$) of water in the nozzle is equal to

$A$ machine gun fires a bullet of mass $65 \, g$ with a velocity of $1300 \, m/s$. The man holding it can exert a maximum force of $169 \, N$ on the gun. The number of bullets he can fire per second will be ............

If the speed of an object is doubled,then which of the following is true?