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. `5sqrt(10)m//s`
B. `10sqrt(5)m//s`
C. `5sqrt(15)m//s`
D. `5sqrt(5)m//s`