A vecter is any physical qvamity that requires both a
magnitude and a direction for its complete description. Exilmples of
vectors encountered in statics are force. position. and moment. A vector
is shown graphically by an arrow, The length of the arrow represents the
magnitude of the vector, and the angle (ซีตา) between the vector and a fixed
axis defines the direction of its line of its line of action, The head or tip of the arrow
indicates the Sense of direction of the vector, Fig. 2-1