In the previous problem, the height at which the two stones will cross each other is

Options

A. 20 m
B. 40 m
C. 60 m
D. 80 m

Answer

D

Explanation

Let stones meet after time `t` and at height `h`.

`A: h=50t-1/2g t^(2) …(i)`
`B: 400-h=1/2g t^(2) …(ii)`
Solving, `t=8 s, h=80 m`