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Sound wave question

  • Thread starter stuti911
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Homework Statement



Sound is detected when a sound wave causes the eardrum to vibrate. Typically, the diameter of the eardrum is about 8.4mm in humans. When someone speaks to you in a normal tone of voice, the sound intensity at your ear is approximately 1 * 10^-6 W/m^2. How much energy is delivered to your eardrum each second?

Homework Equations



I = P/(4pi*r^2)

The Attempt at a Solution



I tried using the equation and I got 2.20×10^−10 W as my answer, but it is wrong. I cannot understand why, because the question seems really simple.
Any help is appreciated, thanks!
 

Answers and Replies

  • #2
collinsmark
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I tried using the equation and I got 2.20×10^−10 W as my answer, but it is wrong. I cannot understand why, because the question seems really simple.
Any help is appreciated, thanks!
The diameter of the eardrum is about 8.4 mm. Which means the radius is half that. :wink:

[Edit: And welcome to Physics Forums!]
 
Last edited:
  • #3
supratim1
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yes, so if you take proper radius you will get the answer.
 
  • #4
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yes, i did take the radius
this is my calculation:
(10^-6)*(0.00001764*4*pi) which gives my the answer above
can any of you try the question?
thanks!
 
  • #5
supratim1
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isn't the answer 5.54*10^(-11)W ?
 
  • #6
supratim1
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first of all, take eardrum as a circle, not sphere, and so use area as pi*r^2
 
  • #7
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allright.. i got it!
thanks a whole bunch :)
 
  • #8
supratim1
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welcome Stuti...would you accept my friend request?
 
  • #9
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welcome Stuti...would you accept my friend request?
Please keep personal messages out of public threads
 

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