Once more on the dynamics of the rattleback (comment on "Strange attractors in rattleback dynamics" by A.V. Borisov and I.S. Mamaev [Usp. Fiz. Nauk 173 407 (2003); Phys. Usp. 46 393 (2003)] and "Nonlinear dynamics of the rattleback: a nonholonomic model" by A.V. Borisov, A.O. Kazakov, S.P. Kuznetsov [Usp. Fiz. Nauk 184 493 (2014); Phys. Usp.57 453 (2014)])
If the motion of a body along a rough surface is modeled such that the point of contact has a zero velocity, in many cases qualitatively incorrect results can be obtained. For the model to be physically valid, it is necessary to take into account the finite contact area and the presence of rotational friction along with the sliding friction.