Question

$\Huge{\star}{\underline{\boxed{\red{\sf{Question :}}}}}{\star}$

If a stone is to hit a point which is at a distance d away and height h above the point from where stone starts, then what is the value of initial speed u if stone is launched at an angle θ.

======================

No Spam! ​

Answer 1

Answer:

answer of question is option B

Answer 2

Hello mate,

Solution:

We know the equation of trajectory is

$y = x \tan( \alpha ) - \frac{g {x}^{2} }{2 {u}^{2} . { \cos }^{2} \alpha } \\ \\ {u}^{2} = \frac{g {x}^{2} }{2(y \tan( \alpha ) - x) { \cos}^{2} \alpha } \\ \\ seperating \: \: terms \: \: we \: \: get \\ \\ \\ {u}^{2} = \frac{ {x}^{2} }{ { \cos }^{2} \alpha } \times \frac{g}{2(x \tan( \alpha ) - y)} \\ \\ u = \frac{d}{ \cos( \alpha ) } \sqrt{ \frac{g}{2(d \tan( \alpha ) - h)} } \\ \\ here \: \: 'x' \: \: is \: \: the \: \: distance \: (d) \: and \: \\ 'y' \: \: is \: \: the \: \: height (h)$

Hope it helps:)