Tippe Top

Solving Newton's second law for translation and rotation produces trajectories of the Tippe Top that are animated below. I taught the students Mathematica to solve the problem, and they taught me how to animate.

Neils Bohr and Wolfgang Pauli are enthralled by the non-intuitive inversion of the tippe top. Why does this top flip over, raising its center of mass and reversing its spin? The inventor of quantum mechanics and the theorist of spin, clearly, are curious, amused, and perplexed. As a physicist, who could ask for more? See the picture at the link below:

Niels Bohr and Wolfgang Pauli watch a Tippe Top.

Richard J. Cohen, The Tippe Top Revisited, Am. J. Phys. 45, 12-17 (1977).