Question

A particle is fired from `A` in the diagonal plane of a building of dimension `20m`(length) `xx` `15m` (breadth) `xx` `12.5 m`(height), just clears the roof diagonally & falls on the other side of the building at `B`.It is observed that the particle is travelling at an angle `45^(@)` with the horizontal when it clears the edges `P` and `Q` of the diagonal. Take `g=10m//s^(2)`.
The speed of the particle at point `P` will be:

A. `5sqrt10m//s`
B. `10sqrt5m//s`
C. `5sqrt15m//s`
D. `5sqrt5m//s`

Answer 1

Correct Answer - A
`PQ` length , `(U^(2) sin 2 theta)/(g) = 25 , U = 5 sqrt(10) m//s`