How High is the Cliff if You Hear the Rock Hit After 7 Seconds?

[devxx]

Homework Statement

Suppose you are climbing in the High Sierra when you suddenly find yourself at the edge of a fog-shrouded cliff. To find the height of this cliff, you drop a rock from the top and 7.00 s later, hear the sound of it hitting the ground at the foot of the cliff.

Part A: Ignoring air resistance, how high is the cliff if the speed of sound is 330 m/s

Homework Equations

V(final)= V(initial)- g
y(final) = y (initial) +Vi(t) - .5 g(t^2)
(Vf)^2=(Vi)^2 - 2g (Yf-Yi)

The Attempt at a Solution

330 = Yi + 0(7) - .5 (9.8)(700)^2
I'm really having trouble just getting past the first part. It seems like it should be pretty straight forward but I'm probably over thinking it.

 

[Anden]

You should try to get two equations: One for the distance traveled by the rock with respect to time, and one for the distance traveled by the sound with respect to time. When you have these you can combine them and get the answer (You will need to rearrange the terms in the equations)