+- phyphox Forums (https://phyphox.org/forums)
+-- Forum: Discussion (https://phyphox.org/forums/forumdisplay.php?fid=1)
+--- Forum: Experiments and Ideas (https://phyphox.org/forums/forumdisplay.php?fid=4)
+--- Thread: Balloon in a bag - measuring pressure (/showthread.php?tid=1490)
Pages:
1
2
RE: Balloon in a bag - measuring pressure - solid - 12-28-2021
Erik,
the time scale of sound is milliseconds and we have seconds between peaks...
Pressure sensor for sound is just a microphone. You can have the sound recording of our balloon pop using the last version of the phyphox corkscrew experiment:
https://phyphox.org/forums/showthread.php?tid=776
Best regards
Mikhail
RE: Balloon in a bag - measuring pressure - Erik Josefsson - 12-29-2021
Yes of course. Apologies. I was confused. The time between measurements is 0.04 seconds though, which matches the sensordb information:
Name LPS331AP Pressure sensor
Vendor STMicroelectronics
Range 1260 hPa
Resolution 0.00024 hPa
Rate 25.0 Hz
Standard deviation 0.061 hPa
In my first measurement (balloon in a bag), the pressure (in the bag) increased from 1014.6 to 1015.4, and then dropped to 1013.8 hPa. The balloon popped at some time between the first (1014.6) and the last pressure measurement (1013.8).
So there are two questions. Why only a one (1) hPa increase when the article cited by wikipedia on the sound pressure level at zero meters from a pop is 11.30 hPa? And why does the pressure drop below the pressure in the bag just before the pop (if that is indeed the case*)?
Subsequent peaks are probably not related to the pop at all.
Am I reading your pop-recording correctly that the pop sound is about 6 ms long? And further that there is a amplitude cut off making it hard to say anything about how loud the pop was?
But you do have a negate a.u. values? Would those not correspond to my pressure drop?
Anyway, it feels like we're not it ideal gas law country at all. I filed my experiment with the wrong intro.
Thanks for taking time!
Best regards.
//Erik
*) Not sure about second question, but I got two similar low-peaks when popping the four balloons without a bag.
RE: Balloon in a bag - measuring pressure - Jens Noritzsch - 01-10-2022
On smartphones inside balloons: https://twitter.com/vcurco/status/1378777037410869251 (deepl should help with the theory)
Such balloons are typically sold as/for gift wraps.