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Homework Help: Tunning Fork

  1. Jun 28, 2011 #1
    1. The problem statement, all variables and given/known data

    A tunning fork with frequency f = 512 Hz is held by someone who swings it vigurously in a circle in the horizontal plane. The radius of the circle is 1.0 m, and the frequency of revolution is 3.0 rev/s. (a) What are the max and the min frequencies that a second person would hear? (b) What part of the rotation corresponds to the highest frequency the second person hears, and which part corresponds to the lowest?

    2. Relevant equations

    1 rev/s = 60 rpm

    1 RPM = 0.01666666667 Hz

    w = 2*pi*f

    3. The attempt at a solution

    I have no idea how to treat this problem! I mean I cannot get the idea for relating this problem with waves and sound equations! Can you help me? Thanx
  2. jcsd
  3. Jun 28, 2011 #2


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    Gold Member

    You should familiarize yourself with the Doppler Effect and related equations before re-attempting this problem.
  4. Jun 28, 2011 #3


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    Gold Member

    Have you studied the doppler effect?

    I think this question is in a funny order, wouldn't you first find the points of max/min shift then find what the shift is there?
  5. Jun 28, 2011 #4
    Hi guys thank you for the hint!

    I already solved the problem with Doppler effect eq. but I still cannot get where is the second person. I mean is he at 1m away from the one who is holding the fork?

    Thank you so much
  6. Jun 28, 2011 #5


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    It doesn't matter where he is. No matter where he happens to be, the tuning fork will always be moving directly towards him at some point in its revolution, and directly away from him at some other point.
  7. Jun 28, 2011 #6
    Yes you're right!

    Thank you so much!
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