# Homework Help: Two wavelengths, find time between successive beats

1. Jan 19, 2009

### phys62

Two pianos each sound the same note simultaneously, but they are both out of tune. On a day when the speed of sound is 348 m/s, piano A produces a wavelength of 0.765 m, while piano B produces a wavelength of 0.772 m. How much time separates successive beats?

So I know:
v=348 m/s
wavelength of A=0.765 m
wavelength of B=0.772 m
f=v/wavelength

so I was able to find the frequency of A=454.9 and frequency of B=450.7
I'm just not really sure what I should be doing... seems like it should be just a one or two step problem.. :/
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

2. Jan 19, 2009

### LowlyPion

OK what is the difference in frequency?

Isn't a beat going to be counted when ever their maxima coincide? So say the difference between 2 tones Δf is 1/2 hz, then won't the time T between maxima be 1/Δf = 2 ?

3. Jan 19, 2009

### phys62

Yes, you're right! Thanks so much!