Vector, originally applied to physics. Many physical quantities such as force, velocity, displacement, electric field intensity and magnetic induction intensity are vectors. Around 350 BC, Aristotle, a famous ancient Greek scholar, knew that force can be expressed as a vector, and the resultant force of two forces can be obtained through the famous parallelogram rule. The word "vector" comes from directed line segments in mechanics and analytic geometry. Newton, a great British scientist, was the first to use directed line segments to represent vectors.