Question on Sound

  • #1
A chimney flue is 15m long from the open top of the chimney to the door at the bottom of the stack that can be opened or closed from within the fireplace. When wind blows over the chimney, a low pitch sound can be heard. Assuming speed of sound is 350m/s and this sound is the air coloumn within the flue resonating at its fundamental frequency, is the dorr at the obttom of the flue opened or closed? Show all work to support your answer! Explain the logic behind your final answer.

thanks. :smile:
 

Answers and Replies

  • #2
Also, i'm not sure what to do here, so please can someone help me out. :shy:
 
  • #3
can someone tell how to start...i'm looking at my notes and text book....and can't find information related to this.
 
  • #4
Doc Al
Mentor
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Standing Sound Waves

Look up standing sound waves in open and closed pipes. (An "open" pipe is one open at both ends; a "closed" pipe is usually closed at one end and open at the other.) Such pipes can resonate at various frequencies. (Think of musical wind instruments.) The fundamental frequency is the lowest one that can create a resonant standing wave in the pipe.

Open and closed pipes of the same length will have different fundamental frequencies.
 
  • #5
HallsofIvy
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1. What is the wave length of a fundamental wave in a 15m pipe
a) closed at one end
b) open at one end

Although I don't see how being told only "a low pitch sound" will help- that's pretty indefinite. You should be able to see immediately that the fundamental frequency of a closed pipe is twice that of an open pipe. Does that help?
 
  • #6
Hurkyl
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Also, we're told more about the sound than it's simply low pitch...
 

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