Two particles A and B are projected simultaneously from two towers of heights 10 m and 20m respectively. Particle A is projected with an initial speed of `10 sqrt(2) m//s` at an angle of `45^@` with horizontal, while particle B is projected horizontally with speed `10 m//s`. If they collide in air, what is the distance d between the towers?

Answer

B

Explanation

In vertical direction,

`S_A = S_B + 10`
`:. (10) t - 1/2 g t^2 = -1/2 gt^2 + 10`
`:. t = 1s`
`underset (S_A)(rarr) underset (S_B)(larr)`
In horizontal direction,
`d = |S_A| + |S_B|`
`= (10) t + 10t = 20t`
`=20m (as t = 1 s)` .