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Homework Help: Determining energy delivered from critical angle

  1. Jan 18, 2013 #1
    Q. An ultrasound shock wave is incident on a kidney stone which is immersed in urine. Using the data below, calculate the critical angle at the urine-kidney stone interface, and thus estimate the energy that will be delivered to the spherical stone. Assume intensity is uniform across the stone.

    [tex]\rho_{urine} = 1000kg/m^{3},
    c_{urine} = 1000m/s,
    \rho_{stone} = 2000kg/m^{3},
    c_{stone} = 4000m/s[/tex]
    Diameter of kidney stone [tex]d = 10mm[/tex]
    RMS intensity of shock wave [tex]I_{rms}=200MW/m^{2}[/tex]

    Attempt at an answer
    I have been able to do the first part of the question. I calculated the critical angle as [tex]\theta_{c}=arcsin(c_{urine}/c_{stone})=22°[/tex]

    However, I don't know how to go from this to determining the energy delivered.

    Thanks for any input.
  2. jcsd
  3. Jan 18, 2013 #2


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    Science Advisor
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    Gold Member

    I don't know enough to answer the question, but I can see that you are missing some relevant equations. Do you have one for transmission coefficient?
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