posted by Sarah .
A PVC pipe that is one meter long is struck and the speed of sound is 345 m/s. What is the fundamental frequency (n=1) of the pipe when:
a.The pipe is open at both ends?
b.The pipe is closed at one end, open at the other?
The phenomenon is called a standing longitudinal wave, or a stationary wave.
The part of the tude Where air does not vibrate is called a node.
In the case of an open tube, the node is at mid-length of the pipe, and the open ends have maximum amplitude. So the length of the tude is half the wave-length of 2 m. The frequency is therefore 345/2=172.5 Hz.
For the tude closed at one end, the node is at the closed end, and maximum amplitude at the open end. The length of the tude is 1/4 of the wavelength of 4 m. The frequency is 345/4=86 Hz.
The following link gives a visual description of the above:
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