Asked by Lyndsay

Part One:
The decibel level of the noise from a jet aircraft
is 130 dB when measured 19.3 m from
the aircraft.
How much sound power does the jet aircraft
emit?
Answer in units of W - 46673.5W

I need help with Part Two:
Part Two:
How much sound power would strike the
eardrum of an airport worker 19.3 m from
the aircraft? (Assume the diameter of the
worker’s eardrum is 1.7 × 10−2m)
Answered by scott
the power is evenly distributed over the surface of a sphere with a radius of 19.3 m

46673.5 W / (4 π 19.3^2) m^2

calculate watts/m^2

calculate the area of the eardrum


FYI ... be aware of significant figures
Answered by Lyndsay
It says this is incorrect
Answered by scott
what is incorrect?
Answered by Lyndsay
When I plug in the answers to that equation and do the work the quest says thats incorrect
Answered by scott
have you learned about significant figures

did you notice the FYI
Answered by Lyndsay
yes, the quest does not care about significant figures
Answered by bobpursley
see my response above. I have an issue with the sphere on a Jet)
Answered by scott
130 dB is equivalent to 10 w/m^2

the area of the eardrum is ... π r^2 = π (8.5E-3)^2 m^2 = 2.27E-4 m^2

10 w/m^2 * 2.27E-4 m^2 = 2.27E-3 W = 2.27 mW (milliwatts)
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