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:

Question

G1 Physics · Accepted Answer

Initial components are uₓ = ucos60° = u/2 and uᵧ = usin60° = √3u/2. At the roof, the velocity is 30° below horizontal, so |vᵧ| = uₓtan30° = u/(2√3). Using vᵧ² = uᵧ² - 2gh: u²/12 = 3u²/4 - 2gh. Hence u² = 3gh and u = √(3gh). Therefore option C.