How Is Sound Intensity Calculated at Different Distances from a Trumpet?

AI Thread Summary
The discussion revolves around calculating sound intensity levels from a trumpet emitting 0.800 W of sound energy. For the sound intensity level directly in front of the trumpet, the area used is that of a circle (πr²) due to the trumpet's bell shape. In contrast, when calculating the intensity level at a distance of 10.0 m, the area of a sphere is used. Participants clarify the distinction between these two areas for accurate calculations. Understanding these area considerations is crucial for solving the problem correctly.
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Homework Statement



When playing fortissimo (very loudly), a trumpet emits sound energy
at a rate of 0.800 W out of a bell (opening) of diameter 12.7 cm. (a) What is the sound
intensity level right in front of the trumpet? (b) If the trumpet radiates sound waves
uniformly in all directions, what is the sound intensity level at a distance of 10.0 m?



The Attempt at a Solution



My only question for the following question has to do with area. I know that I = P / A.. However, for a), since it is at the very end of the trumpet, would the area be pi*r^2, rather than the area for a sphere?

I know that for b) it is the area of a sphere, but I was thinking for a) it would be a circle. Apparently this question is supposed to be hard, so that's why I was thinking that.

Thanks!
 
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You are quite right on all counts.
 
Thank you. I was a bit unsure about the area for a), but it's nice to have some clarification that it is a circle.
 

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