Monday, June 5, 2017

A different spin on things





I found these stones on the beach. They look like normal stones but they're not.





This one I found is called a 'celt' or a wobblestone or a rattleback. It is a semi-ellipsoidal stone which will rotate on its axis in a preferred direction. If spun in the opposite direction, it becomes unstable, "rattles" to a stop and reverses its spin to the preferred direction. This spin-reversal appears to violate the law of the conservation of angular momentum.



Next time you go to the beach, take a bread board or a piece of plywood maybe and see if you can discover one or two canoe shaped stones that can spin on a flat surface and then magically spin in the opposite direction. 





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