Scalars Vs Vectors

In science and engineering we frequently encounter quantities that have magnitude and
magnitude only: mass, time, and temperature. These we label scalar quantities, which remain
the same no matter what coordinates we use. In contrast, many interesting physical
quantities have magnitude and, in addition, an associated direction. This second group
includes displacement, velocity, acceleration, force, momentum, and angular momentum.
Quantities with magnitude and direction are labeled vector quantities. Usually, in elementary
treatments, a vector is defined as a quantity having magnitude and direction. To distinguish
vectors from scalars, we identify vector quantities with boldface type, that is, V.
Our vector may be conveniently represented by an arrow, with length proportional to the
magnitude. The direction of the arrow gives the direction of the vector, the positive sense
of direction being indicated by the point.