  The mechanical response of a circularly-driven disk in a dissipative medium
is considered. We focus on the role played by viscous friction in the spinning
motion of the disk, especially on the effect called reverse rotation, where the
intrinsic and orbital rotations are antiparallel. Contrary to what happens in
the frictionless case, where steady reverse rotations are possible, we find
that this dynamical behavior may exist only as a transient when dissipation is
considered. Whether or not reverse rotations in fact occur depend on the
initial conditions and on two parameters, one related to dragging, inertia, and
driving, the other associated with the geometric configuration of the system.
The critical value of this geometric parameter (separating the regions where
reverse rotation is possible from those where it is forbidden) as a function of
viscosity is well adjusted by a q-exponential function.
