rm common misunderstanding about "real" and "imaginary" terminology
can be thought of as numbers which can be represented by some infinite or finite decimal representation, such as 0.707106781187.. . They are called "real" because they actually exist in the real world, i.e. measures, weights, temperatures and so on are all real numbers, as opposed to the [[imaginary number]]s, which are just an abstract concept, but do not really exist.
In classical physics, measurements of things that can vary smoothly and continuously, like [[speed]] or [[temperature]], are treated as real numbers.