By measurement you determine that sound waves are spreading out equally in all d

Question

By measurement you determine that sound waves are spreading out equally in all directions from a point source and that the intensity is 2.4×102 W/m2 at a distance of 4.3 m from the source.

Part A

What is the intensity at a distance of 3.5 m from the source?

Express your answer using two significant figures.

Part B

How much sound energy does the source emit in one hour if its power output remains constant?

Express your answer using two significant figures.

By measurement you determine that sound waves are spreading out equally in all directions from a point source and that the intensity is 2.4×102 W/m2 at a distance of 4.3 m from the source.

Part A

What is the intensity at a distance of 3.5 m from the source?

Express your answer using two significant figures.

Part B

How much sound energy does the source emit in one hour if its power output remains constant?

Express your answer using two significant figures.

Explanation / Answer

I = P/A

A =4pi*r^2

I' = P/4pi*r'^2

I/I' = r'^2/r^2

I' = I*r^2/r'^2 = 3.6 x 10^-2 W/m^2

P = I*A

P = 2.4 x 10^-2 * 4pi * (4.3)^2

P = 5.576 W for 1s

for one hour = 3600s

P = 2 x 10^4 W

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