A solid cylinder (disk) and a hollow cylinder (hoop)
with equal masses and equal radii are simultaneously allowed
to start from rest and roll a common distance down an inclined
plane of fixed angle. The times to reach the bottom are compared.
Also, in different demonstrations, times are compared for (1)
solid cylinders of different masses and radii, (2) solid spheres
of different masses and radii, and independently, (3) a solid
sphere and a solid cylinder.