Motion of a Ball Rolling on a Rotating Disc

This paper is a more academic approach of a work published in 1986 by J.M. Levy-Leblond that studies the surprising motion of a ball rolling on a planar surface and arriving on a rotating disc. The observation shows that the ball rolls on the planar surface with a velocity vector in an initial direction, then crosses the rotating disc along a curved trajectory, and finally leaves the rotating plate without changing its initial direction and velocity. The application of the fundamental laws of classical mechanics in a König frame linked to the mass centre of the ball allow to show that the curved trajectory is circular, with a constant velocity in modulus.