**Geometry & Physics: Rolling** - A type of motion that combines rotation (commonly, of an axially symmetric object) and translation of that object with respect to a surface (either one or the other moves), such that, if ideal conditions exist, the two are in contact with each other without sliding.

**Image 1:** Four objects racing down a plane while rolling without slipping. From back to front: spherical shell (red), solid sphere (orange), cylindrical ring (green) and solid cylinder (blue). The time for each object to reach the finishing line depends on their moment of inertia around the rolling axis.

**Image 2, 3:** Common moments of inertia & Rolling Farms by Jason Arney.

**Source:** Rolling on Wikipedia & Common moments of inertia at ph.utexas.edu