Question

A jet plane at take-off can produce sound of intensity 9.00 W/m2 at 31.0 m away. But you prefer the tranquil sound of normal conversation, which is 1.0 μW/m2. Assume that the plane behaves like a point source of sound.

Part A What is the closest distance you should live from the airport runway to preserve your peace of mind? Express your answer using two significant figures. r =   km   SubmitMy AnswersGive Up Part B What intensity from the jet does your friend experience if she lives twice as far from the runway as you do? Express your answer using two significant figures. I =   μW/m2   SubmitMy AnswersGive Up Part C What power of sound does the jet produce at take-off? Express your answer using two significant figures. P =   W

Answer 1

Answer(a):

Given:

P1 = 9.00 W/m2

P2 = 1.0 μW/m2

R2= 31 m

We knows that--

P2 / P1 = (R1/ R2)^2
R1/ R2 = sqrt( P2/P1)
R1 = R2 * sqrt( P1/ P2)
= 31 * sqrt( 9000000/1)
R1 = 93 km                                      Answer

Answer(b)

Your friend will experience 1/4 the P1

= ¼ * 9 = 2.25 W/m2                       Answer

Answer(c)

P = 4 * π * 31^2 * 9

= 108.6 kW                                                Answer