A ** vector** has both **magnitude*** and*
**direction**. A **scalar** is a
**magnitude** only.
In these notes, a vector is represented ** boldface**, such as **A**. In
the text, or when written by hand, a vector is shown with an arrow on
top. Writing A (not bold, without an arrow), or |A| means the **magnitude **of the vector.

Pictorially, a vector is an arrow whose length equals the magnitude of the vector. Rules for multiplying a vector by a scalar are illustrated below: