# Sound wave frequency in tube

1. Aug 4, 2009

### Puchinita5

1. The problem statement, all variables and given/known data
A sound wave of the form s = sm cos(kx - ωt + φ) travels at 347 m/s through air in a long horizontal tube. At one instant, air molecule A at x = 2.04 m is at its maximum positive displacement of 6.40 nm and air molecule B at x = 2.08 m is at a positive displacement of 2.10 nm. All the molecules between A and B are at intermediate displacements. What is the frequency of the wave?

2. Relevant equations

3. The attempt at a solution
uhhh i'm pretty much confused from the get go...i'm not sure how air molecules interact with a wave???? i might need to be spoon fed a little here, cuz i don't even know where to start!! ANY HINTS GREATLY APPRECIATED :)

2. Aug 4, 2009

### ideasrule

Sound is basically the vibration of air molecules: as molecules oscillate, they force their neighbors into the same type of motion. Sound being a wave, some air molecules vibrate more than others, like how the middle of a guitar string vibrates more than the string's ends. Need any more hints?

3. Aug 4, 2009

### Puchinita5

ahhh sorry yea, i have NO idea....didn't even know the middle of a guitar string vibrates more than the ends (and totally don't know why)...