If a rock is dropped off of a sea cliff, and the sound of the rock hitting the water is heard 3.4 seconds later, how tall is the cliff, assuming the speed of sound is 340 m/s.(adsbygoogle = window.adsbygoogle || []).push({});

What I've been trying to do is break the problem up into 2 parts, one for the rock going down towards the sea, and one for the speed of sound going up the cliff. The problem is that I can't seem to substitute the right things into the equation x = x0 + v0t + .5at^2. For the going down part, the equation looks like the following:

X= 0 + 0 + (.5)(9.8)t^2. And for the going up part, I'm not sure whether the initial velocity of the speed of sound is 340 m/s, or whether it is zero. If the initial speed were 340 m/s, then the equation would (?) look like the following:

x = 0 + 340t + 0.

This is where I get stuck, and I don't know what to do with the two equations. I would greatly appreciate the help. Thanks.

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: If a rock is dropped off of a sea cliff

**Physics Forums | Science Articles, Homework Help, Discussion**