Question

1. A rock is thrown horizontally off a cliff. I the cliff has a height h, and the rock has an impact angle θ with the surface of the water at the base of the cliff (see diagram), find an expressionin terms of some or all of 0, h, and g) for the initial speed with which the rock is thrown. [8 pts

Answer 1

time taken from A to B, h = vy_1 t + 1/2 g t^2 h = 0 x_1 + 1/2 g t^2 h = 1/2 g t^2 = > t = squareroot 2h/g velocity at B, v_y_2 = v_y_1 + 2t V_y_2 = 0 + 2 squareroot 2h/2 = > v_y_2 = squareroot 2gh Since v_x = v = constant So, tan Q = v_y_2/v_x = > tan Q = squareroot 2gh/v v = squareroot 2gh/tan Q