1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: A few sound problems

  1. Mar 15, 2007 #1
    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
  2. jcsd
  3. Mar 15, 2007 #2
    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.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook