A person throws ball with velocity from the top of a building in vertically upward direction the ball reaches the ground with a speed of 3v then the height of the building is :

Options

A. `(4v^(2))/(g)`
B. `(3v^(2))/(g)`
C. `(6v^(2))/(g)`
D. `(9v^(2))/(g)`

Answer

a

Explanation

Let h be the height and x be the maximum height of the ball above the building to which it rise. Then we have
`x=(v^(2))/(2g)` and `h+x=(3v)^(2)/(2g)`
`:. H=(9v^(2))/(2g)-(v^(2))/(2g)=(4v^(2))/(g)`