A jet aeroplane is flying at a constant height of 2 km with a speed `360 kmh^(-1)` above the ground towards a target and releases a bomb. After how much time it will hit the target and what will be the horizontal distance of the aeroplane from the target so that the bomb should hit the target ? (Take `g = 10 ms^(-2))`

Options

A. 10s, 1km
B. 20 s, 2km
C. 30s, 3km
D. 40s, 4km

Answer

B

Explanation

Given, `H = 200 m, u = 360 kmh^(-1)`

`u = 360 xx (5)/(18) = 100 ms^(-1)`
The time taken by the bomb to hit the target is
`T = sqrt((2H)/(g)) = sqrt((2 xx 2000)/(10)) = 20s`
The horizontal distance of the aeroplane from the target
`R = u sqrt((2H)/(g)) = 100 xx 20 = 2000 m = 2km`