Comments on the paper "Terminal retrograde turn of rolling rings"

TL;DR

This paper challenges previous explanations of the retrograde turn of rolling rings, showing through experiments and theory that aerodynamic drag is not the primary cause, and that such motion can occur in both rings and disks without slipping.

Contribution

It provides experimental and theoretical evidence that the retrograde turn is not mainly caused by aerodynamic effects, broadening understanding of rolling dynamics.

Findings

Drag torque is not the main cause of retrograde turn.

Retrograde turn can occur in both rings and disks without slipping.

Theoretical analysis supports the possibility of retrograde motion in different shapes.

Abstract

Mir Abbas Jalali et al. [Phys. Rev. E 92, 032913(2015)] explained the retrograde turn of rings by aerodynamic phenomena due to the presence of a central hole in the ring as opposed to a disk. The results of our experiments suggest that the drag torque is not the main reason for the retrograde turn of the rings, and the results of theoretical research have shown that such a motion is possible for both the ring and the disk in the case of rolling without slipping.