On the influence of friction on the motion of a top

Abstract

A simple calculation gives, to a first approximation, the influence of sliding friction on the motion of a top, spinning on a horizontal plane.

For a spherical body with axially symmetric mass distribution two effect are found:

1. The centre of gravity will be lifted if it lies eccentric in the sphere;

2. the axis with the greatest moment of inertia moves towards the vertical, if the principal momenta are unequal.

The equilibrium condition for the combination of the two effects is derived.

The rising of the tippe top is ascribed to sliding friction.

An ordinary top, describing its common regular precession, will usually roll; rolling friction contributes to the rising of the top.