A stone is thrown vertically upwards with an initial speed `u` from the top of a tower, reaches the ground with a speed `3 u`. The height of the tower is :

Options

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

Answer

B

Explanation

`upsilon^(2)=u^(2)+2gh`
`rArr (3u)^(2)=(-u)^(2)+2gh rArr h=(4u^(2))/(g) darr + ve`