Tippe Top

The Tippe Top inverts itself when spinning at sufficient speed. It does this because its centre of mass does not coincide with the geometrical centre of sphere.

Credits: Tom Strong Reviews

When the Tippe Top is spun on a table, the top will quickly turn the stem down towards the table. When the stem touches the table, the top will invert and start spinning on the stem.

Because the geometrical center of the sphere does not coincide with the center-of-mass, the point of contact with the surface will not coincide with the rotational axis.

Because the point of contact does not coincide with the rotational axis, the Tippe Top will slide over the surface in a circle around the rotational axis. The sliding friction supplies the torque needed for the inversion of the top.

History

In the 1800's, Sir William Thomson and Hugh Blackburn experimented by rotating eggshaped stones found on the beach. They saw properties similar to those of the Tippe Top, yet to be invented.

A description of this story is found in a book by John Perry from 1890. Perry describes a small spherical object with a center-of-mass which does not coincide with the center of the sphere. When the object is put on a table, it will point the center-of-mass down towards the table. Then the object is spun, and it lifts its center-of-mass just like a Tippe Top.

In 1891, the top was patented as "Wendekreisel" in Germany by Helene Sperl from Munich. The patent ran out the year after because the patent fee was not paid.

Credits: FYSIKBASEN.DK

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