A rock is thrown horizontally with speed v from the top of a cliff of height H.

Question

a.) Identify an equation that can be used to solve for the time it takes the rock to hit the ground.

b.) Rearrange the equation you wrote to solve for the time it will take the rock to hit the water.

c.) Identify an equation that can be used to solve for the horizontal distance between the bottom of the cliff and the place where the rock lands.

d.) Rearrange the equation you wrote to solve for the horizontal distance D between the bottom of the cliff and the place where the rock lands. Answer in terms of H, v, and physical constants if necessary.

Answer 1

I assume the bottom of the cliff, the ground, and the water are at the same level (this was not stated clearly in the problem).

(a)

If there is no air resistance,

H = gt²/2.

where

t = time

g = acceleration of gravity

(b)

t = (2H/g)^1/2

(c)

D = vt,

with t computed in part (b).

(d)

D = v (2H/g)^1/2