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Homework Help: Sound wave and energy can you help me?

  1. Mar 16, 2007 #1
    A sound wave with intensity 2x10^(-3) W/m^2 is perceived to be modestly loud. Your eardrum is 6.0 mm in diameter. How much energy will be transferred to your eardrum while listening to this sound for 1.0 min?

    =2x10^(-3) * (pi (6x10^-3)^2)
    =2.2610x10^-7 W

    P=delta E/ delta t
    =2.2610x10^-7 J/s * 60 s
    =1.3572x10^-5 J

    But this is not the right answer. I have no idea what I did wrong. Can someone please help me? Any help is greatly appreciated! Thanks!
  2. jcsd
  3. Mar 16, 2007 #2


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    For one thing the diameter is 6mm. Not the radius. Change your pi*r^2 number.
  4. Mar 16, 2007 #3
    Thanks for pointing it out! I rarely make this kind of silly mistake:surprised
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