Addition of vectors by rectangular Components

 

A physical quantity that has only magnitude but no direction is called a scalar quantity. For example, speed, distance, mass, volume, density, work, time, temperature, energy, charge, entropy, frequency, and any real number. Scalars are indicated by letters of ordinary type as in elementary algebra. Operations with scalars follow the same rules as in elementary algebra.

On the other hand a physical quantity that has both magnitude and direction is called a vector quantity. For example, displacement, velocity, weight, force, acceleration, momentum, torque, magnetic field intensity, and electric field intensity. Graphically a vector is represented by an arrow defining the direction, the magnitude of a vector being indicated by the length of the arrow. The tail end of the arrow is called origin or initial point of the vector, and the head  is called the terminal point or terminus. Analytically a vector is represented by a letter with an arrow over it,