Question

what is a null vector?

Answer 1

In mathematics, given a vector space X with an associated quadratic form q, written, a null vector or isotropic vector is a non-zero element x of X for which q(x) = 0. 

Answer 2

$\Huge \bf{\green{Null\: Vector}}$

★ It is a vector having zero magnitude and an arbitrary direction .

✫ Physical meaning of Null vectors is clearly we can understand by the examples :-

✱ The position vector of the origin of the co-ordinate Axes is a null vector .

✱ The displacement of a stationary body with the passage of time is Null Vector .

✱ The displacement of a body thrown up and received back by the thrower is a null vector .

✱ The velocity vector of a stationary body is a zero vector .

✱ The acceleration vector of body in uniform motion is a zero vector, etc.

✱ The Null vector is only for mathematical importance .