rotational_mechanics.gif (17954 bytes)

MOMENT OF INERTIA - 
A HOOP AND A DISK ON AN INCLINED PLANE








EQUIPMENT
    redball.gif (326 bytes) Hoop
    redball.gif (326 bytes) Disk
    redball.gif (326 bytes) Inclined Plane



NARRATIVE
            The moment of inertia of a hoop is its mass times its radius squared (mr2). The moment of inertia of a disk is ˝ its mass times its radius squared (˝mr2). The linear velocity of a rolling disk is twice the linear velocity of a hoop of equal mass.

            The hoop and disk have equal mass. Place them at the top of the inclined plane and release them simultaneously. The disk reaches the bottom in nearly ˝ the time it takes the hoop.