A vector is a quantity or phenomenon that has two independent properties: magnitude and direction. The term also denotes the mathematical or geometrical representation of such a quantity.

Examples of vectors in nature are velocity, momentum, force, electromagnetic fields, and weight. (Weight is the force produced by the acceleration of gravity acting on a mass.) A quantity or phenomenon that exhibits magnitude only, with no specific direction, is called a scalar . Examples of scalars include speed, mass, electrical resistance, and hard-drive storage capacity.

Vectors can be depicted graphically in two or three dimensions. Magnitude is shown as the length of a line segment. Direction is shown by the orientation of the line segment, and by an arrow at one end. The illustration shows three vectors in two-dimensional rectangular coordinates (the Cartesian plane) and their equivalents in polar coordinates.

Compare vector graphics . Also see scalar .

21 Sep 2005