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

Step-by-step solution

Using equation of motion for projectile in x and y-direction. h = u sin θ t - 1 2 g t 2 d = u cos θ t or t = d u cos θ ⟹ h = u sin θ . d u cos θ - 1 2 g . d 2 u 2 cos 2 θ ⟹ u = d cos θ g 2 d t an θ - h