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Homework Help: Intensity of periodic sound waves

  1. Jun 30, 2010 #1
    1. The problem statement, all variables and given/known data
    A firework charge is detonated many meters above the ground. At a distance of 400m from the explosion, the acoustic pressure reaches a maximum of 10.0 N/m2. Assume that the speed of sound is constant at 343 m/s throughout the atmosphere over the region considered, that the ground absorbs all the sound falling on it, and that the air absorbs sound energy as described by the rate 7.0 dB/km.

    What is the sound level (dB) at 4.00km from the explosion?

    2. Relevant equations

    B(dB)=10log(I/Io); I=(deltaPmax)^2/(2pv)=Power/Area

    3. The attempt at a solution

    I plug the data into the equations but it give me the wrong answer. I don t know why the answer is 65.6dB. Especially how to use the acoustics pressure?
  2. jcsd
  3. Jun 30, 2010 #2
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