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A stone projected at an angle of 60^@ fr...


A stone projected at an angle of `60^@` from the ground level strikes at an angle of `30^@` on the roof of a building of height `h`. Then the speed of projection of the stone is:

A

`sqrt(2gh)`

B

`sqrt(6gh)`

C

`sqrt(3gh)`

D

`sqrt(gh)`

Text Solution

Verified by Experts

The correct Answer is:
C
Let initial and final speeds of stone be `u` and `v`.
`:. V^(2)=u^(2)-2gh` …….`(1)`
and `v cos 30^(@)=u cos 60^(@)` ……..`(2)`
solving 1 and 2 we get `u=sqrt(3gh)`
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