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Homework Help: Measuring the sound of fireworks.

  1. Jun 3, 2012 #1
    1. The problem statement, all variables and given/known data

    A firework charge is detonated many metres above the ground. At a distance of d1 = 590 m from the explosion, the acoustic pressure reaches a maximum of ΔPmax = 10 Pa (see figure below). Assume the speed of sound is constant at 343 m/s throughout the atmosphere over the region considered and the ground absorbs all the sound falling on it. Assume that the density of air is 1.2 kg/m^3. What is the sound level at a distance of d2 = 3.50 ×103 m from the explosion?

    2. Relevant equations

    3. The attempt at a solution

    so we know that pmax=10Pa when observer is 590m away

    10= 343×1.2×ω×590

    solving for ω

    ω= 10 / (343×590×1.2)

    now to find p when Smax= 3.50×103

    p = 343×1.2×(10 /(343×590×1.2))×(3.5×103)

    p= 59.322

    I= P /4∏r2

    I= 59.322 / 4∏(3.5×103)2

    I= 3.8536×10-7

    β=10log10(3.85361×10-7 / 10-12)

    β = 55.859 dB

    this seem like the right method.??.thanks
    Last edited: Jun 3, 2012
  2. jcsd
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