On the Retrograde Rolling of Rings

Synopsis

Careful observers will notice that a rolling ring undergoes a mysterious change of direction in its final stages of motion. Like a rolling disk, the ring’s center of mass initially oscillates about an inward spiral trajectory. But before rattling to rest, the ring’s motion inflects and is sent spiraling in the opposite direction. This so-called “terminal retrograde turn” defies the classical mechanics which effectively describes rolling disks. By comparing simulation and high-speed imaging, the researchers expose the subtle effect responsible for the retrograde turn.

Citation: M. A. Jalali, M. S. Sarebangholi, and M. R. Alam, “Terminal retrograde turn of rolling rings.” Physical Review E, 92(3), (2015).