Question

A gun mounted on the top of a moving truck is aimed in the backward direction at angle of ${30}^o$ to the vertical. If the muzzle velocity of the gun is $4m/s$, the speed of the truck to send the bullet vertically up is

• A. $1m/s$
• B. $\frac{\sqrt{3}}{2}m/s$
• C. $0.5m/s$
• D. $2m/s$

Answer 1

The correct option is D $2m/s$

$V$ $=$ vel. of truck
$u$ $=$ muzzle level of gun
$\theta ={60}^o$
$\therefore V=ucos\theta$

Speed of truck should be such that in horizontal direction velocity of bullet cancels out.

$\Rightarrow u\sin {30}^o-V=0$
$v=\frac{4}{2}=2m/s$