# Important Definitions Related To Vectors Contents

## (I) Polar Vectors

Vector which have a starting point or a point of application are called polar vectors.

Example:- Force, Displacement etc

## (II) Axial Vectors

Vectors which represent the rotational effect and acts along the axis of rotation are called axial vectors.

Example:- Angular Velocity, Angular Momentum, Torque etc.

## (III) Modulus Vectors

The magnitude of a vector is called modulus of that vector.

Example:- For a vector A, It is |A|.

## (IV) Unit Vector

A vector having magnitude equal to unity but having a specific direction is called a unit vector.

A unit vector A is written as A^.

A^ = A/|A|

In Cartesian coordinate i^, j^ and k^ are the unit vectors along X,Y and Z Axis respectively.

## (V) Null Vector

A vector with magnitude zero and having an arbitrary direction is called null vector.

Example:- The velocity vector of a stationary object.

## (VI) Equal Vector

Two vectors are said to be equal if they have equal magnitude and same direction.

## (VII) Negative Vector

Two vectors are said to be the negative vectors of each other, if their magnitutes are equal but direction are opposite.

## (VIII) Collinear Vectors

Two or more vectors are said to be collinear, when they act along the same lines or parallel lines.

Example:- Tug of war

## (IX) Coplanar Vectors

The vectors lying in the same plane are called coplanar vectors.

## (X) Co-Initial Vectors

The vectors which have the same initial point are called Co-Initial Vectors.

## (XI) Orthogonal Unit Vectors

If two or three unit vectors are perpendicular to each other, they are known as orthogonal unit vectors.

Example:- The unit vectors along X, Y and Z Axis are denoted by i^, j^ and k^. these are orthogonal unit vectors.

## (XII) Localised Vectors

Those vectors whose initial point is fixed are known as localised vectors.

Example:- Position vector of a particle, initial point lies at the origin.

## (XIII) Non-Localised Vectors

Those vectors whose initial point is not fixed are known as non-localised vectors.

Example:- Velocity vector of a particle moving along a straight line.