A rifle shoots a bullet with a muzzle velocity of `400 m s^-1` at a small target `400 m` away. The height above the target at which the bullet must be aimed to hit the target is `(g = 10 m s^-2)`.

Options

A. 1 m
B. 5 m
C. 10 m
D. 0.5 m

Answer

B

Explanation

(b) Time taken by bullet to reach the target is
(Distance)/(Velocity) = (Distance)/(u cos theta) [As theta is very small, `cos theta = 1`]
Time = `(Distance)/(u) = (400)/(400) = 1 s`
Vertical deflection of bullet is
=`(1)/(2) "gt"^2 = (1)/(2) xx 10 xx (1)^2 = 5 m`.