An aeroplane is travelling horizontally at a height of 2000 m from the ground. The aeroplane, when at a point P, drops a bomb to hit a stationary target Q on the ground. In order that the bomb hits the target, what angle `theta` must the line PQ make with the vertical ? (`g = 10 ms^(-2))`

Explanation

(B) Let t be the time taken by bomb to hit the target.
`h=2000=(1)/(2)"gt"^(2)rArrt=20` sec.
`R=ut=(100)(20)=2000m`
`because tan theta=(R)/(h)=(2000)/(2000)=1rArr theta=45^(@)`