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Homework Help: Waht does standing wave with both ends open has 396hz mean?

  1. Jul 1, 2011 #1
    1. The problem statement, all variables and given/known data
    A standing wave in a pipe with both ends open has a frequency of 396 Hz. The next higher harmonic has a frequency of 662 Hz.

    (a) Determine the fundamental frequency.

    answer: 266 Hz

    (b) How long is the pipe?
    answer : 0.645 m

    3. The attempt at a solution

    i'm not sure how to solve this problem

    f1 = v/(2L)

    i thought of using algebraic equations for 396 and 662

    396 hz = 2v/(2L)
    662 hz = 3v/(2L)

    but then it doesn't work
    i am not sure....

    i have the answers

    266 hz = 343/ (2*0.645)
    which works as the fundamental perfectly
    but when i set 396 hz as 2nd harmonic and 662 hz as 3rd it doesn't work

    and if the fundamental for open pipe both sides is 266 the next harmonic must be times 2 of f0, but it is not

    thank you
  2. jcsd
  3. Jul 1, 2011 #2


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    Homework Helper

    This pipe is rather one end closed, I am afraid.

  4. Jul 1, 2011 #3
    i got it
    the answer to the first question is 608 hz - 400hz = 208 hz

    and the 2nd is 343/2/208 = 0.825m
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