rotation

A rotation is a circular movement of an object around a center (or point) of rotation. A three-dimensional object can always be rotated about an infinite number of imaginary lines called rotation axis ( AK-seez). If the axis passes through the body's center of mass, the body is said to rotate upon itself, or spin. A rotation around an external point, e.g. the planet Earth around the Sun, is called a revolution or orbital revolution, typically when it is produced by gravity. The axis is called a pole.

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