Physics Quantities
Scalars
and
Vectors
Scalar:
• A quantity that is described by magnitude only.
• You add scalar quantities like you normally add
numbers.
• 5 mL of water added to 5 mL of water will give you 10
mL of water.
• Some examples of scalars are
–
–
–
–
–
Distance
Speed
Mass
Time
Volume.
Vector:
• A quantity that is described by stating its
magnitude and direction.
• You must learn special methods to add vectors
(see below).
• Some examples of vectors are
– Displacement
– Velocity
– Acceleration
– Force.
Vectors (cont.)
• Vectors are represented by arrows (directed
line segments).
• A vector has a head and a tail.
• The length of the arrow, when drawn to some
self-determined scale, represents the
magnitude of the vector and its direction is
the way it points in 3-dimensional space as
you sight from tail to head.
Tail
Head
Vectors (cont.)
• They can be added graphically by placing the
arrows head to tail.
• The arrow that extends from the tail of the first
vector to the head of the last vector is called the
resultant.
• It indicates both the magnitude and direction of
the vector sum.
Vector A
Vector B
Resultant = Vector A + Vector B
Vectors (cont.)
• Remember, vectors don't always have to be in
a straight line but may be oriented at angles to
each other, such as
Vector A
Vector B
Resultant = Vector A + Vector B
Vectors (cont.)
• Vectors can be added in any order.
Vector B
Vector A
Resultant = Vector B + Vector A
Vectors (cont.)
Vector A
Vector B
Resultant = Vector A + Vector B
Vectors (cont.)
• More than two vectors can be added together
using the head-to-tail method.
Vector A Vector B Vector C Vector D
Resultant = Vector A + Vector B + Vector C + Vector D
Vectors (cont.)
Resultant vectors can be
determined by a number of
different methods. You will solve
vector addition exercises both
graphically and with vector
components.