A pebbel is thrown horizantally from the top of a `20` m high tower with an initial velocity of `10 m//s`.The air drag is negligible . The speed of the peble when it is at the same distance from top as well as base of the tower `(g=10 m//s^2)`

Options

A. `10sqrt2 m//s`
B. `10sqrt3 m//s`
C. `20 m//s`
D. `25 m//s`

Answer

B

Explanation

The pebble is at same distance from top and base of the tower after is falls down by a distance `h=10 m`

By using `v^(2)=u^(2)+2` as we have
`v=sqrt((10)^(2)+2(10)(10))=10sqrt3 m//s`