### Video Summary:

Basic Terminology
A scalar is a magnitude
E.g. 45 pounds
A vector quantity is a
magnitude with direction
E.g. 50 mph east. Vector OP
First letter represents the
initial point
Second letter represents
the terminal point
Vector OP and vector PO
are not the same vectors.
They have the same magnitude,
but in opposite directions. Two vectors are equal if and only if they both have the same magnitude and direction.
The sum of two vectors A and B
Place the initial point of B at the terminal point of A. The vector with the same initial point as A and the same terminal point as B is the sum A + B.
The parallelogram rule: place the vectors so that their initial points coincide. Then complete the parallelogram as shown in the figure.