1. The problem statement, all variables and given/known data An object emitting a sound with a 400hz frequency is thrown 10m away and passes right next to you. At 10m away, you can barely hear the object and you have average hearing. When the object passes you, you observe a sound with a frequency of 435hz. Find the loudness in dB when the object was 2 meters away. Assume the object was headed straight towards you. 2. Relevant equations L = 10 log(I/Io) = 20 log(P/Po) Io = 10-12 W/m2 I = Pav/A = 1/2 Po2/ρv Doppler's Effect: fs (v/(v-vo)) = fr v = speed of sound ≈ 343 m/s 3. The attempt at a solution So to solve for this I need to solve for I with little information. To solve I believe I will need to solve for the initial velocity of this object. Solving for vo vo = v - fsv/fr = 343m/s - 400hz/435hz * 343 m/s = 27.6 m/s Would Po be the amplitude of the sound wave? I'm really not sure how to tackle this problem. I think that since you can barely hear it at 10m away means something too. That means that initially the loudness is 0dB. λ = v/f = 343m/s / 400hz = .8575m Really not sure what I am doing. Any help would be appreciated!