Chapter 11: The Wobbler
The Wobbler is a geometric device invented by Frederick Flowerday some years ago. It consists of two interlocked circles. The planes of the circles are orthogonal and the centers of the circles are separated by √2√2 times the common radius. In practice, it is made from two circular discs, each with a radial notch. When the Wobbler is rolled on a plane, it executes a most fascinating wobbly motion. Observation indicates that the center of gravity remains at, or nearly at, constant height. We demonstrate that it does remain at constant height and that this holds if and only if the separation of centers is √2 times the radius. We also study the distance between the points of contact and show that this is constant if and only if the separation of centers is equal to the radius. Such a device was invented by Paul Schatz [1]…
If it is not easy to visualize the geometry then consider a huge version, called "Rocking Toy" that was made by the artist Anthea Alley, in Figure 11.1. The holes are for artistic reasons only.
