A stone is thrown upwards with initial velocity 'u' from top of a tower and it reaches to ground with velocity '3u' then height of the tower is ......

A stone is thrown upwards with initial velocity 'u' from top of a towe

1.	A stone is thrown upwards with initial velocity 'u' from top of a tower and it reaches to ground with velocity '3u' then height of the tower is ......
Answer» `(3u ^(2))/(g) ` `(4U ^(2))/(g)` `(6u^(2))/(g)` `(9u^(2))/(g)` Solution :`(3u) ^(2) -U^(2) =2gh` `(because v = 3u, u=u, a = g and x=h)` `THEREFORE 9u^(2) -u^(2) =2gh` `therefore h = (8u^(2))4u^(2))/(g)`