A heavy uniform bar of mass
rests on top of two identical rollers that are continuously and rapidly turned in opposite directions with angular speed
. The centers of the rollers are at a distance
apart. The coefficient of kinetic friction between the bar and the roller surfaces is
, a constant independent of the relative speed of the two surfaces. The bar, held at rest with its center at distance
from the midpoint of the two rollers, is released at
. This Demonstration depicts the subsequent motion.