Rolling Motion

Rolling motion — a ring, disc, sphere or wheel rolling along a surface — is among the most commonly observed forms of motion in everyday life, from a rolling ball to every wheeled vehicle on the road. Consider, concretely, a disc rolling along a horizontal surface, and a specific point $P$ marked on its rim. As the disc rolls, this point $P$ undergoes translational motion together with the disc's center of mass, and, simultaneously, rotational motion about that same center of mass — rolling is genuinely a combination of both kinds …