A hemispherical tippe top

Abstract

A conventional tippe top consists of a hollow, truncated sphere with a short peg at the top so that the top can easily be spun between the thumb and index finger of one hand. A simpler version is described in the present paper, consisting only of a hemispherical shell. When spun about a vertical axis at moderate speed, the shell rises and completely inverts. A hemispherical shell therefore acts in the same way as a conventional tippe top, but with two main differences. One is that it spins in the opposite direction about its axis of symmetry. The other is that it precesses on its rim after inversion, in a manner similar to a spinning disk.