# Homework Help: Sound Waves

1. Mar 11, 2014

### JeanDucreaux

1. A sound wave with frequency f = 2300Hz is sent into a circular tube of radius R=160cm through an opening at some point A.
A receiver lies at point B, separated from A by an angle α=130°. The speed of sound in air is v=330 m/s.
Sound propagates from A to B in both directions along the tube.
(a) What level of interference do you observe at B?
(b) What happens if the frequency is lowered to f1=230 Hz?
(c) And to f2= 23Hz?

2. I guess, I have to calculate the periphery of the circle with given R, and hence divide Δx with λ, which would give me n. If its closer to a whole number, it would result in a constructive interference. With questions (b) and (c), my guess is, that it does not change the level of interference, since 230 and 23 are multiple integers of 2300 (factor 10).

2. Mar 11, 2014

### BvU

Hello Jean, and welcome to PF.

Well, what do you find under (a)? What's against showing your results ?
And for (b) and (c) I wouldn't guess, but either see that yes, it is as you suspect, or no, factors of 10 can make a considerable difference!

3. Nov 11, 2014

### somegirl

can u guys help me pls?
i got an exam tomorrov and I realy need your help!
When the sound goes from surface to another(for example from water to air) what satys the same
a)period b)amplituda c) elongacioni d) frekuenc

4. Nov 12, 2014