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Homework Statement
A concert loudspeaker suspended high off the ground emits 28.0W of sound power. A small microphone with a 0.900cm^2 area is 51.0m from the speaker.
A) What is I at the microphone?
B) How much sound energy impinges on the microphone in J?
Homework Equations
I = P/A
I = 4pir^2
The Attempt at a Solution
I have solved the answer to part A):
I = 28W/4pi(51)^2 = 8.57*10^-4 W/m^2The answer to part B is what's eluding me:
I know that at the microphone I = 8.57*10^-4 W/m^2
So:
8.57*10^-4 = P/.009m^2
P = 7.713*10^-6 W which is equal to J/s
Therefore my answer would be 7.713*10^-6 J of sound energy are impinged each second.
Mastering Physics is disagreeing with me. Any advice?
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