A '''rotation''' is a movement of an object in a [[circular]] [[motion]]. A [[two]]-[[dimensional]] object rotates around a [[center]] (or point) of rotation. A [[three]]-dimensional object rotates around an imaginary line called an [[axis]]. If the axis of rotation is within the [[body]], the body is said to rotate upon itself, or spin—which implies [[relative]] [[speed]] and perhaps free-movement with angular [[momentum]]. A circular [[motion]] about an external point, e.g. the [[Earth]] about the [[Sun]], is called an [[orbit]] or more properly an orbital [[revolution]]. | A '''rotation''' is a movement of an object in a [[circular]] [[motion]]. A [[two]]-[[dimensional]] object rotates around a [[center]] (or point) of rotation. A [[three]]-dimensional object rotates around an imaginary line called an [[axis]]. If the axis of rotation is within the [[body]], the body is said to rotate upon itself, or spin—which implies [[relative]] [[speed]] and perhaps free-movement with angular [[momentum]]. A circular [[motion]] about an external point, e.g. the [[Earth]] about the [[Sun]], is called an [[orbit]] or more properly an orbital [[revolution]]. |