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

$A$ machine gun fires $20$ bullets per second into a target. Each bullet weighs $150 \, g$ and has a speed of $800 \, m/s$. Find the force necessary to hold the gun in position.

$A$ cricket ball of mass $0.25 \,kg$ with speed $10 \,m/s$ collides with a bat and returns with the same speed within $0.01 \,s$. The force exerted on the bat is: (in $\,N$)

Figures $(a)$,$(b)$,$(c)$ and $(d)$ show the variation of force with time. The impulse is highest in which figure?

In an hour-glass,approximately $100$ grains of sand fall per second (starting from rest); and it takes $2 \, s$ for each sand particle to reach the bottom of the hour-glass. If the average mass of each sand particle is $0.2 \, g$,then the average force exerted by the falling sand on the bottom of the hour-glass is close to .......... $N$.

$A$ mass of $1 \ kg$ is suspended by a string $A$. Another string $C$ is connected to its lower end. If a sudden jerk is given to string $C$, then: