  The present paper reports a novel behavior involving regular polygons with n
sides and filled to varying degrees with granular materials. These are
comprised of a set of hollow polygons produced on a 3D printer, and a single
larger hollow hexagon fabricated with wooden sides and clear Plexiglas faces.
Empty or full polygons stop immediately at shallow ramp angles, and roll the
full length of the ramp for steep ramp angles, approaching a terminal velocity.
This is consistent with results previously reported by other investigators of
rolling solid polygons and partially filled cylinders. In contrast, partially
filled polygons released at shallow ramp angles accelerate to a "terminal
velocity," but then come to an abrupt stop. The distance traveled is
reproducible and dependent on the ramp angle, number of sides and the volume
fill ratio and is minimized when filled to 0.4 of its total internal volume.
For larger ramp angles, the partially filled polygons again approach a
"terminal velocity," but the terminal velocity is minimized, again near the
fill ratio of 0.4. a simple model is introduced, but it is successful only in
replicating the overall trend in velocity as a function of time for the large
angle cases.
