"Centrifugal force: A gedanken experiment"—new surprises

A recently proposed gedanken experiment [G.Z. Machabeli and A.D. Rogava. Phys. Rev. A 50, 98 (1994)], exhibiting surprising behavior, is reexamined. A description of this behavior in terms of the laboratory inertial frame is presented, avoiding uncertainties arising due to a definition of a centrifugal force in relativity. The surprising analogy with the radial geodesic motion in Schwarzschild geometry is found. The definition of the centrifugal force, suggested by J.C. Miller and M.A. Abramowicz, is discussed.