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Vanessa23
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According to the text, at a distance of 50 m from a jet engine, the sound intensity is 10 W/m2. This corresponds to a loudness (or an intensity level) of 130 dB. [You should convince yourself that this is true.] If you find the sound too loud and you want to reduce the intensity by a factor of 10, to what new distance (approximately) from the jet engine should you move to achieve this reduction?
I=P/Area
Intensity level = 10db*log(I/Io)
to find the power of the jet engine:
p=10*((50^2)*4pi)
=314159
a factor of 10 reduction would mean 13dB
13=10log(I/10^-12)
1.3=log(I)-log(10^-12)
-10.7=log(I)
I=10^-10.7
A=P/I
A= 314159/ 10^-10.7
A=1.57x10^16
1.57x10^16 = 4pi r^2
r=397289
so does that mean that you really can't make the intensity decrease by a factor of 10?
I=P/Area
Intensity level = 10db*log(I/Io)
to find the power of the jet engine:
p=10*((50^2)*4pi)
=314159
a factor of 10 reduction would mean 13dB
13=10log(I/10^-12)
1.3=log(I)-log(10^-12)
-10.7=log(I)
I=10^-10.7
A=P/I
A= 314159/ 10^-10.7
A=1.57x10^16
1.57x10^16 = 4pi r^2
r=397289
so does that mean that you really can't make the intensity decrease by a factor of 10?
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