The distance R from source to observer is given by v = R/t or

R = vt (340 m/s)(4.0s) = 1360 m

Since IL = 92 db = 10 log(I/I0)

then I/I0 = 109.2 and I = 109.2(10-12) = 1.58X10-3 W/m2

I = P/4pR2 and P = E/t

Therefore E = Pt = I(4pR2)t

E = (1.58X10-3 W/m2)(4p13602m2)(0.200s) = 7.4X103 J

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