Vectors
SCALAR AND VECTOR QUANTITIES
Rev. 0
Page 1
CP02
Figure 1 Vector Reference Axis
SCALAR AND VECTOR QUANTITIES
Scalars are quantities that have magnitude only; they are independent of direction.
Vectors have both magnitude and direction. The length of a vector represents
magnitude. The arrow shows direction.
EO 1.1
DEFINE the following as they relate to vectors:
a.
Scalar quantity
b.
Vector quantity
Scalar Quantities
Most of the physical quantities encountered in physics are either scalar or vector quantities. A
scalar quantity is defined as a quantity that has magnitude only. Typical examples of scalar
quantities are time, speed, temperature, and volume. A scalar quantity or parameter has no
directional component, only magnitude. For example, the units for time (minutes, days, hours,
etc.) represent an amount of time only and tell nothing of direction. Additional examples of
scalar quantities are density, mass, and energy.
Vector Quantities
A vector quantity is defined as a quantity that has both magnitude and direction. To work with
vector quantities, one must know the method for representing these quantities.
Magnitude, or "size" of a vector, is also
referred to as the vector's "displacement." It
can be thought of as the scalar portion of the
vector and is represented by the length of the
vector. By definition, a vector has both
magnitude and direction. Direction indicates
how the vector is oriented relative to some
reference axis, as shown in Figure 1.
Using north/south and east/west reference
axes, vector "A" is oriented in the NE
quadrant with a direction of 45 north of the
o
EW axis. G iving direction to scalar "A"
makes it a vector. The length of "A" is
representative
of
its
magnitude
or
displacement.

