# Homework Help: Waves question involving 3 people in a tunnel

1. Jun 2, 2013

### bookerdewitt

1. The problem statement, all variables and given/known data
Becky and Rajiv are standing at different points in a long tunnel while Naoimi adjusts her bass amplifier at one end. As Naoimi plays an 88Hz tone, BEcky cannot hear much and Raj complains that the volume is too loud. What is the minimum distance between Becky and Rajiv?(Use 343 m/s for speed of sound).

2. Relevant equations
v=f x lambda
L=lambda/2 x n, n being the harmonic and L being the length

3. The attempt at a solution

So I calculated the wavelength as being 3.9m for the 88hz tone and I figure Raj must be closer to Naomi then Becky but I don't understand how you would know which harmonic the tone would be so I cant use the length formula at all.

2. Jun 2, 2013

### Staff: Mentor

"Plays an 88Hz tone" implies no appreciable harmonic content.

You have sketched the standing wave pattern?

3. Jun 2, 2013

### bookerdewitt

No I havent. How would I even know what it looks like?

4. Jun 3, 2013

### haruspex

Treat the tunnel as a pipe of unknown length. The standing wave produced will have nodes and antinodes, alternating. How far apart will they be? Is it a node or antinode:
- at the loudspeaker
- at Becky
- at Rajiv?

5. Jun 3, 2013

### Staff: Mentor

[Broken]

Last edited by a moderator: May 6, 2017