How intensity and amplitude depends from a distance r

AI Thread Summary
The discussion focuses on how the intensity and amplitude of a sound wave from a line source depend on the distance from the source. It establishes that intensity is related to the power divided by the area, with the area increasing as the square of the distance (A ∝ r²). Consequently, intensity decreases with the square of the distance (I ∝ r⁻²). The confusion arises from interpreting the area of sound propagation, with some participants unsure about the correct approach. Ultimately, the thread reflects a lack of clarity in understanding the problem, leading to minimal engagement.
AndreAo
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Homework Statement


A line source of sound (for instance, a noisy freight train on a straight track) emits a cylindrical expanding sound wave. Assuming that the air absorbs no energy, find how (a) the intensity I and (b) the amplitude sm of the wave depends on the perpendicular distance r from the source.

Homework Equations


Intensity = Power/Area

The Attempt at a Solution


I thought that the area would be something like the base of a circular cone, and the area of it base would A \propto r². Then I \propto r⁻². Is the reasoning right?
 
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what is this？I totally confused
 
A relatively ancient (yr 2009) post that had no replies. Likely no-one at the time could interpret the problem statement cogently either. Best to just move on and let it rest.
 

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