A stone is dropped from the top of tower. When it has fallen by `5 m` from the top, another stone is dropped from a point `25m` below the top. If both stones reach the ground at the moment, then height of the tower from grounds is : (take `g=10 m//s^(2)`)

Options

A. `45 m`
B. `50 m`
C. `60 m`
D. `65 m`

Answer

A

Explanation

Vel. of 1st stone when passing at `A to `
`V^(2) -0+2.10.5`
`V=10 m//s `
`S_(1)-S_(2) =20 m`
`rArr (10t +1/2 10.t^(2))-((1)/(2).10.t^(2))=20`
t=2s
`S_(2)=(1)/(2).10.4=20 m`
`Ht =25+20 =45 m`.