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A "Rattleback" undergoes a spin reversal that, at first, appears to violate conservation of angular momentumpic.twitter.com/cU2TMaW3Gr
The physics behind the Rattleback is however nontrivial In short, the spin reversal results from the misalignment between the principal inertia & curvature axes, which couples the spinning with the pitching and the rolling oscillations https://arxiv.org/pdf/1704.06717.pdf …
If it did that floating in free space I'd be concerned about conservation of angular momentum.
For sure, but the motion definitely made me double take after trying to work in out for 30 mins i felt like I was either being a dunce or it was non-trivial, per the usual for me
Isn’t this a special case of the intermediate axis theorem? It is just changing the circular motion for oscillatory (which are basically the same for such small angles)
no, the inertia tensor is completely non-diagonal in the coordinate basis.. the angular momentum and rotation axis are hence misaligned in general, for one .. you can also see that the angles in this demonstration don't admit small angle approximation
The Dhzanibekov effect:https://www.youtube.com/watch?v=1VPfZ_XzisU …
That is a fancy one! I made a short video about the cheaper plastic ones that still work pretty well: https://www.amazon.com/Rattleback-Plastic-Assorted-Colors-Teachers/dp/B004P6E984/ref=sr_1_1?keywords=celt+rattleback&qid=1570851660&sr=8-1 …https://youtu.be/_KRmexfQQ4E
Metal? Plastic? All well and good if you’ve got that kind of wealth and energy. Me? I waited until my bar of shower soap wore down just right.
@asevrin63 your cup of tea?
I did show you this in my 2nd year mechanics course, didn’t I? Together with the tippy top. Rigid bodies are a lot of fun!
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