Some quantities, like force, velocity and displacement require magnitude and direction to completely describe them. These are called vector quantities.
Vectors are special mathematical creatures that look like arrows.
They are written as a number and unit, the vector s magnitude , plus a directional part telling where a vector is pointing. Vectors are represented by letters the letters appear in bold face like x, a , and i . It is easier to type them in bold face but it may be easier to draw vectors on paper with the little arrow on top. The magnitude of the vector can be written as the absolute value of the vector, for example the magnitude of is . Just place the tip of one vector to the tail of the other.