A gun movunted on the top of a voing truck is aimed in the backward direction at an angle of ` 30^@` to the vertical. If the muzzle velocity of the bullet firee from the gun is ` 4 ms^(-1)`, then the speed of the truck that will make the bullet come out vertically is.

Options

A. ` 0.5 ms ^(-1)`
B. `1.0 ms^(-1)`
C. ` 1. 5 ms^(-1)`
D. ` 2. 0 ms^(-1)`

Answer

D

Explanation

Refer to Fig. 2 (CF). 60. the horizontal component velocity of bullet
` = 4 cos 60^@ with ` -x direction`
` = 4 xx 1//2 =- 2 ms^(-1)` along x-direction
.
The bullet will come out vertically with velocity
` = 4 sin 60^@ = 4 xx sqrt 3//2 =2 sqrt 3 ms^(-1)` if horizontal velocity of bullet and truck is zero . It will be zero if the velocity of truck ` =0 -(- 2 ms^(-1))`
` =2 ms^(-1) ` along x-diretion.