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A student stands at the edge of a cliff and throws a stone horizontally over the

ID: 1682823 • Letter: A

Question

A student stands at the edge of a cliff and throws a stone horizontally over the edge with a speed of 14.0 m/s. The cliff is h = 65.0 m above a flat horizontal beach, as shown in the figure below.

How long after being released does the stone strike the beach below the cliff?
1

With what speed and angle of impact does the stone land?
2 m/s
3° below the horizontal

Explanation / Answer

The time taken by the body to reach the ground is h = 0.5 gt^2 ==> t = [2 h / g]^1/2 = [2 * 65 / 9.8]^1/2 = 3.642 s The final speed of the stone v = [Vx^2 + Vy^2]^1/2 = [Vx^2+g^2*t^2]^1/2 = [14^2 + (9.8 * 3.642)^2]1/2 = 38.34 m/s angle theta = tan-1 ( Vy/Vx) = tan-1 (9.8 * 3.642 / 14) = 68.58 deg