An aeroplane is flying at a height of 2000 m above the ground horizontally with a uniform speed of 720 km/h. At what angle of sight (w.r. to the horizontal) should the pilot drop a bomb so as to hit target on the ground ?

Options

A. 26°.57
B. 30°.2
C. 41°.3
D. 20°.41

Answer

A

Explanation

Here horizontal speed of the aeroplane = `720xx5/18`
`200ms^(-1)`
Height h = 2000 m
Now let x be the horizontal distance, then
`h=0+1/2g t^(2)`
or, `2000=1/2xx10t^(2)`
`t=20sec`
x = ut = `200 xx 20`Now `tantheta=h/x=2000/4000`
`=1/2`
or `theta=tan^(-1)0.5=26^@57.`