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Homework Help: Pressure/standing waves

  1. Oct 12, 2006 #1
    Hi there

    Could someone please help with these questions.

    A helmholtz resonator has a resonant freq. of 100Hz. draw graphs showing how the pressure and displacement of the air in the neck vary with time. how would these be different at the position of a listener some distance away...

    i can draw the graphs but I'm unsure of the part about the listener being some distance away...??

    and the 2nd one is ....explain how a standing wave can be formed by travelling waves, and hence how the frequencies of standing waves on a stretched string are related to the speed at which waves travel along the string?

    all i know is that waves would be travelling in opposite directions..canceliing out..? is this even right?...any help much appreciaited

  2. jcsd
  3. Oct 12, 2006 #2


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    Staff: Mentor

    -1- The resonator will have a partial standing wave in it (partial because some of the sound energy has to get out the open end to propagate to the listener.

    -2- What is the equation for a travelling wave? What do you get if you combine a left-travelling wave and a right-travelling wave? Also, what is the relationship between the velocity of propagation of a wave on a string, in comparison to the tension of the string and the linear mass density of the string?
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