|To this moment, we have classified physical quantities as either basic
or derived quantities. Another way of classifying physical quantities is
using scalars and vectors. Scalar quantities are those which can be communicated
with just the magnitude (size) of the quantity, for example, a person
may have a mass of 55 kg, and this is all we need to know about someone's
mass. Vectors, are communicated with a magnitude and direction.
Imagine yourself in a hiking trip. You arrive at the destination, and phone the rangers to ask where the waterfall is. The ranger may tell you "it is 150 meters away." Is this useful? Of course not!! Is it 150 meters North or is it 150 meters East? The ranger must also specify a direction!
Vector quantities are expressed by a magnitude,
followed by direction.