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How does a whip break the sound barrier? (Slow Motion Shockwave formation) - Smarter Every Day 207
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Dec 01, 2021
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nuccy on
Supersonic Trebuchet
Fun fact, you can accelerate an almost-everyday object to supersonic speeds: whip tip [1,2].1. https://en.wikipedia.org/wiki/Whipcracking
2. https://www.youtube.com/watch?v=AnaASTBn_K4 (very much recommended)
⬐ system2Anyone interested, amazon sells Bullwhips for $23. Almost got one.⬐ injidupI have one at home. They are awesome fun. But you only get a few cracks off before people start poking their heads out of windows. They are easily as loud as a small firearm.⬐ fhoFunny thing: a friend of mine lives in rural Bavaria, with a very old, conservative land-lady. The kind that will call you once you exceed your lawful one hour of instrument practice time per day.Still, she allowed rehearsals in the backyard from what can only be called a music formation comprising accordion ... and bull-whips.
Like literally whipping to the beat of the music, hours of staccato whip cracking. I honestly had no idea that that existed. Example: https://www.youtube.com/watch?v=QquXdrDcX7I
⬐ system2Wow. What.⬐ injidupAs an Australian living very close to Bavaria I can tell you that ain't Bayern! Oida! ;) https://www.youtube.com/watch?v=yY6nminL9wY is what you are looking for.
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Mar 08, 2019
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wolfram74 on
Nasa captures images of supersonic shockwaves
As mentioned by others, the photography technique looks like (and apparently is a software enabled variant of) Schlieren photography. This(1) is a neat example of an old school Schlieren set up capturing shockwave formation during whip cracks. I highly recommend it.
⬐ nate_meurerVery cool. They didn't mention this in the video, but I immediately see one groundbreaking new phenomenon that they uncovered: at the exact moment the end of the whip goes supersonic, it is being accelerated by something other than the tension of the rope. It looks as though it's accelerated by the shockwaves, of which there appear to be two -- one on each side of the whip end, with a vacuum in between. It's as clear as day in the video. The rope in front of it clearly goes lax, and the whip end even changes direction to align with the shock wave propagation.⬐ nate_meurerI thought about this and watched the video again, and I've changed my mind just a bit. It looks like, instead of being accelerated, the whip end is experiencing reduced drag in the vacuum between the two shock waves. We can see that it travels right behind the first shockwave, not lagging at all, and this is exactly what you would expect if it is both the source of the shockwave and the beneficiary of the vacuum behind it.