# Homework Help: Sound homework help please

1. Nov 8, 2005

### Physic_Scholar

Ok I need guidance on how to approach this problem. The problem is as follows: A stone is dropped from the top of a cliff. The splash it makes when striking the water below is heard 3.5s later. How high is the cliff?

2. Nov 8, 2005

### Physic_Scholar

Does anyone know the answer to this problem?

3. Nov 8, 2005

### thenewbosco

the time is of course the time for it to fall plus the time for the sound to come back up. So therefore use $$d=\frac{1}{2}at^2$$ and $$v_{sound}=\frac{d}{t}$$ then you solve both for time and add them together to produce 3.5 and hence solve for d.

4. Nov 8, 2005

### Physic_Scholar

ok I had those equations I just didn't think what to do. CAn you help me with this problem also: At a rock concert, a dB meter registered 130 dB when placed 2.8m in front of a loudspeaker on the stage. What is the power output of the speaker, assuming uniform spherical spreading of the sound and neglecting absorption in air?

Someone help me plz?

Last edited: Nov 8, 2005