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A few sound problems

by Gauss177
Tags: sound
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Mar15-07, 01:10 AM
P: 38
1. The problem statement, all variables and given/known data
1. An unfingered guitar string is 0.70 m long and is tuned to play E above middle C (330 Hz). How far from the end of this string must the finger be placed to play A above middle C (440 Hz)?

2. An organ is in tune at 20 degrees C. By what fraction will the frequency be off at 0 degrees C?

2. Relevant equations

3. The attempt at a solution

1. I used the v=(freq)(wavelength) equation:
v = (330)(0.70) = 231 m/s
Then i plugged in 231 to figure out the distance for 440 Hz:
(231 m/s) = (440)x
x=.525 m
I'm not sure if my method is right, so please check that! thanks

2. Not sure about this one

Thanks for the help
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Mar15-07, 05:31 AM
P: 1,017
I think that's right.

For the second part,
[tex]v=\sqrt{\frac{\gamma RT}{M}}[/tex] The temperature should be in Kelvin. Since there is no change in the gas, [tex]\frac{\gamma R}{M}[/tex] are constant, and so the speed of sound varies with the square root of temperature. That should help you out.

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