The Spinning - Top

If we make the top spinning, it stands up on its little foot. The reason of this extraordinary behaviour is not so clear know; friction is a decisive factor.

The energy dissipated under the influence of the friction's force is bigger if the spinning-top spins on its larger pole (medium moment of friction force is bigger at equal pressure). Therefore, the spinning-top tends to reduce the friction surface at the cost of rising its barycentre. The enhancement of potential energy is possible by a reduction of the rotation speed.

Lofty physicists (Niels Bohr and Wolfgang Pauli) tried to finds tips on this top already at the beginning of XX century. The exact solution is far from being easy.