A storne is dropped from the `25` th storey of a multistored building and it reaches the ground in `5 s`. In the first second, it passes through how many storey of the buliding?

Options

A. `1`
B. 2
C. 3
D. none

Answer

A

Explanation

Suppose h be the height of each storey then `25h=0+(1)/(2)xx10xxt^(2)=(1)/(2)xx10xx5^(2)` or `h=5m` In first second let stone passes through n storey.
So `nxx5=(1)/(2)xx10xx(1)^(2)` or `n=1`