The intensity level of sound 30 m from a jet airliner is 120 dB.At what distance from the airplane will the sound intensity level be a tolerable 100 dB? (Assume spherical spreading of sound. )
A) 60 m
B) 90 m
C) 300 m
D) 400 m

Question

Quizplus · Accepted Answer

Using the inverse square law for spherical spreading of sound, we have:
I1/I2 = (r2/r1)^2
Where I1 is the initial sound intensity level, I2 is the tolerable sound intensity level, r1 is the initial distance from the source, and r2 is the distance we are trying to find.
Plugging in the given values, we get:
120/100 = (30/r2)^2
Solving for r2, we get:
r2 = 300 m

The Intensity Level of Sound 30 M from a Jet