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 . Find the speed of projection of the stone in ms- 1 . Take h=30m,g=10ms- 2

Question

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 . Find the speed of projection of the stone in ms- 1 . Take h=30m,g=10ms- 2 <img class="img-fluid question-image" alt="Question" src="https://cdn.tardigrade.in/q/nta/p-gkq40txwehgir1mn.jpg" /> (A)  (B)  (C)  (D)

Tardigrade Admin · Accepted Answer

Let initial and final speed of stone be u and v. ∴ v2=u2-2gh And vcos30° =ucos60° Solving above equations we get u=√3 g h

Q. A stone projected at an angle of $6 0^{\circ}$ from the ground level strikes at an angle of $3 0^{\circ}$ on the roof of a building of height $h$ . Find the speed of projection of the stone in $m s^{- 1}$ . Take $h = 30 m, g = 10 m s^{- 2}$

Let initial and final speed of stone be $u$ and $v .$
$∴ v^{2} = u^{2} - 2 g h$
And $v cos 3 0^{\circ} = u cos 6 0^{\circ}$
Solving above equations we get
$u = 3 g h$

Q. 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 . Find the speed of projection of the stone in ms−1 . Take h=30m,g=10ms−2

Let initial and final speed of stone be u and v. ∴v2=u2−2gh And vcos30∘=ucos60∘ Solving above equations we get u=3gh​

Q. A stone projected at an angle of $6 0^{\circ}$ from the ground level strikes at an angle of $3 0^{\circ}$ on the roof of a building of height $h$ . Find the speed of projection of the stone in $m s^{- 1}$ . Take $h = 30 m, g = 10 m s^{- 2}$

Let initial and final speed of stone be $u$ and $v .$
$∴ v^{2} = u^{2} - 2 g h$
And $v cos 3 0^{\circ} = u cos 6 0^{\circ}$
Solving above equations we get
$u = 3 g h$