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Homework Help: How do you find the displaced amplitude of sound?

  1. Jan 13, 2009 #1
    1. The problem statement, all variables and given/known data

    A loudspeaker of 30cm diameter vibrates at 2kHz. Given that the pressure generated is 55.1N/m2, determine the displaced amplitude.
    Assume air density is 1.59kg/m3 and that the speed of sound is 340m/s.

    I have been told that the dimensions given for the loadspeaker is a red herring and not needed in the solution of hte question.

    How do you find the displaced amplitude of sound?

    2. Relevant equations

    3. The attempt at a solution

    v = Velocity = 340m/s
    f = Frequency = 2kHz = 2000Hz
     = Wavelength =

    Wavelength  = 0.17m (170cm)
  2. jcsd
  3. Jan 16, 2009 #2


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    Staff Emeritus
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    Welcome to PF :smile:

    I don't know the answer myself, but is there nothing in your textbook or class notes relating the amplitude of vibration for sound waves?

    p.s. some characters you are typing are not showing up properly, for example in "xxx = Wavelength =", the "xxx" (whatever that is) does not show up.
  4. Jan 16, 2009 #3
    Yes I saw the missing characters after I posted it.

    I worked it out after I posted the message.

    I have the answer at work so I will post it and how I got it later.
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