Just curious. Not sure if this has been discussed already, and I'm not sure what the phenomenon is called, but here's a description: I have a heavy gold class ring that I got from my alma mater. I put the ring face down on the desk, flat, and it can rest like that because the face of the ring is flush with the desk. The ring face is a flat oval-shaped face about 1cm in diameter. Now I can 'spin' the ring, like you would do with a coin or a top. Very quickly, the ring, while spinning rapidly, somehow flips up so the face is no longer in contact with the desk, but is facing skyward, and continues spinning, barely losing any momentum at all. I have tried to watch the transition carefully, at some point the ring MUST be completely sideways right before it flips up, which is just seems kinda crazy to me. Why? Probably something basic, but as an EE I don't do a lot of mechanics, and this has been a question rattling around in my head for a long time.