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corkscrew and speed of sound.
Hi !

Here is an experiment i created to measure the speed of sound while opening a good bottle of wine !

Cheers !

It works also fine if you make the "pop" with a finger in a test-tube !

Attached Files Thumbnail(s)

.phyphox   tire bouchon.phyphox (Size: 59.57 KB / Downloads: 1,341)
Julien, thanks for the useful phyphox code with many images. You have even took into account the end correction 0.61 D !!
Only a photo of the bottle used in the experiment is absent and it is unclear what equation has to be used Tongue .

As I understood, you have used the approximation by the \lambda/4 standing wave in a tube closed at one side.
If you have not yet finished the bottle an approximation by the Helmhotz resonator is more appropriate for the next opening.
You're right !
The air column in the bottleneck act as a one-sideclosed pipe resonator. The peak frequency is the one of the quarter wavelength standing wave.

The formula used is :

Cair = 4 f0 (L + 0,61xD)
I was insired by this paper :

And of course, once the bottle is open and some wine has been drunk, one can use the formula of the Helmotz resonnator instead ! May be i will add it in a few days !

Here is a result with a test tube.
The end correction for a one-side closed pipe is a half of 0.61 D, i.e. 0.3 D ... as in the paper you have cited.
Big Grin 
Oups !

Here is the corrected version.
I will have to open a new bottle this evening !!! Big Grin


.phyphox   tirebouchon.phyphox (Size: 59.57 KB / Downloads: 636)
Dear Julien.

For a test tube with L = 23.7 cm and D = 2.8 cm your program gives f = 375.0 Hz and c_air = 381 m/s, to high...
Strange, but the standard "Audio spectrum" of phyphox gives f = 351 Hz (c_air = 345 m/s) - much more acceptable
By the way the resonance peak of our "Resonance curve" gives f = 362 Hz ...

It is very important to measure the temperature around the bottle of wine to be opened. I would suggest to add a feature to your program: determination of the temperature from c_air using a simple formula t = (c_air/20)² - 273 (°C) .



Peter Froehle,  "Finding the Outdoor Temperature Using a Tuning Fork and Resonance", 
The Physics Teacher 44, 358 (2006);

Jeffrey D. Goldader, "Determining Absolute Zero Using a Tuning Fork", 
The Physics Teacher 46, 206 (2008);
Thank you for these  interesting articles !

There is some strange behaviour with your test tube indeed !

I try some experiments with mine. I put it in the oven few minutes and i found a frequency of  515.63 Hz for a measured air temperature inside the tube of 65°C. This gives a speed of 370.37 m/s. It seems to be a pretty good result.
Then i tried with the test tube in the freezer for a few minutes. With a measured air température of -5°C i found a frequency of 468.75 Hz. Exactly the same as in the room temperature of about 20°C.
 Strange !!!
I had pretty good result by hitting the open end of 250mL graduated cylinder with my open hand ! Less than 5% of error.

Here is the video :

I always wanted to look closer at the determination of the resonance by FFT. It is strange, when you repeat the experiment , the resonance frequency  f0 remains exactly the same ??!.. I have found a very similar but not exactly the same graduated cylinder (nominative 250 mL) but I got exactly the same f0... So, I have plotted the resonance part of the measured FFT spectrum together with direct measurements of the resonance by frequency sweeping (see 'acoustic resonance' in this forum). The interval between points in FFT is very large (46.875 Hz) and a good result can be obtained only by chance. This is also the answer to some questions asked here earlier. In order to reduce this interval we have to increase the time of the sound treatment..
Yes, you're right !!!
Thanks for sharing this idea !
I will improve it.

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