Two paper screens `A` and `B` are separated by a distance of `100m`. A bullet pierces `A` and `B`. The hole in `B` is `10 cm` below the hole in `A`. If the bullet is travelling horizontally at the time of hitting the screen `A`, calculate the velocity of the bullet when it hits the screen `A`. Neglect resistance of paper and air.

Options

A. `100 ms^(-1)`
B. `200 ms^(-1)`
C. `600 ms^(-1)`
D. `700 ms^(-1)`

Answer

D

Explanation

`h = (1)/(2) g t^(2)` (in vertical direction)
`:. T = sqrt((2h)/(g)) = sqrt((2 xx 0.1)/(10)) = 0.141 s`
Now in horizontal direction, `v_(x) = (S_(x))/(t) = (100)/(0.141) ~~ 700 ms^(-1)`