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Homework Help: Sound Waves: Energy per second

  1. Feb 11, 2015 #1
    1. The problem statement, all variables and given/known data
    Standing 20m away from a tower generating 2500W of power how much energy/s hits each of your eardrums?
    Surface area of eardrum=55mm^2
    Assume that the speaker generates sound uniformly in a forward hemisphere.

    2. Relevant equations

    3. The attempt at a solution
    Surface area of eardrum=55mm^2=55*10^-6m^2
    The actual answer is 5.5*10^-5W, not sure what went wrong.
  2. jcsd
  3. Feb 11, 2015 #2


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    Note that the sound spreads over a hemisphere (not a sphere).
  4. Feb 11, 2015 #3
    Oh that's sneaky, I'll have to pay more attention to that stuff in the future.
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