I have several questions about the motion of spinning coins. I won't get to them all in this post, but hopefully some of you can help get me started. (Note: I am a mathematician, not a physicist - that might help color your responses.) First I want to think about spinning an idealized penny - a perfect disk with radius, R, width W, and constant density, ρ. 1. Would you expect such a coin to tend to spin on the flat of it's edge or on one of the corners? I would expect the corners for two reasons: First, friction is minimized when the coin is on a corner and second the center of mass is at its highest point when the coin spins on a corner: 1'. I have noticed that objects spinning at very high speeds seem to move their center of mass to the highest point possible. Two prime examples are the Tippe Top and the hard-boiled egg. Is this a general phenomenon, or are these two examples special cases? I would expect it to be a general phenomenon due to the very large angular velocity causing an upward force on the object, but I really can't say why... 2. I would expect the coin to ideally spin in a perfectly balanced state; however, as the coin spins I expect friction to cause small perturbations in this state making the coin wobble from a perfectly balanced state. When such a wobble occurs, I would expect the coin to stand itself back up into an upright state if the angular velocity is large enough and start the slow descent downwards if the angular velocity is not large enough. But, the question is: What is "large enough?" If given a perturbation that causes the coin to tilt to an angle of θ with the z-axis, is it possible to determine the angular velocity needed to "stand the coin back up?" Thanks for any insight you can give me!