Post 9: Vektor Part 3

           Some physical quantities such as length, area, volume and mass can be completely described by a single real number. Because these quantities are describable by giving only a magnitude, they are called scalars. [The word scalar means representable by position on a line; having only magnitude.] On the other hand physical quantities such as displacement, velocity, force and acceleration require both a magnitude and a direction to completely describe them. Such quantities are called vectors.

If you say that a car is traveling at 90 km/hr, you are using a scalar quantity, namely the number 90 with no direction attached, to describe the speed of the car. On the other hand, if you say that the car is traveling due north at 90 km/hr, your description of the car's velocity is a vector quantity since it includes both magnitude and direction.

To distinguish between scalars and vectors we will denote scalars by lower case italic type such as a, b, c etc. and denote vectors by lower case boldface type such as u, v, w etc. In handwritten script, this way of distinguishing between vectors and scalars must be modified. It is customary to leave scalars as regular hand written script and modify the symbols used to represent vectors by either underlining, such as u or v, or by placing an arrow above the  symbol..