Q. A boy throws a stone from the edge of a cliff with an initial speed (Vo) at an angle of 30 degrees above the horizontal. when it hits the surface of a lake 22m below the top of the cliff, the stone is moving at a speed of 25 meters per second. what was its initial velocity.
Let the initial speed was vo m/s at an angle 30 degree above the horizontal.
By law of conservation of energy:
With formulas and explanations, the problem is solved.