Question

Define null vector.

Answer 1

Hint: Vectors are essential in physics because they can explain the velocity and acceleration of a moving object as well as the forces acting on it. Many additional physical quantities may be conceived of in the same way. Although most of them do not indicate distances, the length and direction of an arrow may nevertheless be used to express their magnitude and direction.

Complete answer:
 The coordinate system used to describe a physical vector has an impact on its mathematical representation. Pseudovectors and tensors are other vector-like objects that express physical quantities and transform in a similar fashion when the coordinate system changes.A null vector is a directionless vector with magnitude equal to zero.

It's the product of two or more equal vectors acting in opposite directions. Pulling a rope from both ends with equal pressures in opposing directions is a classic example of a null vector. In mathematics, a null vector or isotropic vector is a non-zero member x of X for which q(x) = 0. Given a vector space X with an associated quadratic form q, written (X, q), a null vector or isotropic vector is a non-zero element x of X for which q(x) = 0.

Definite quadratic forms and isotropic quadratic forms are different in the theory of real bilinear forms. They are differentiated by the fact that only the latter has a nonzero null vector. A pseudo-Euclidean space is a quadratic space (X, q) with a null vector.

A non-unique decomposition of a pseudo-Euclidean vector space into orthogonal subspaces A and B, X = A + B, where q is positive-definite on A and negative-definite on B, is possible.
$$\bigcup _{r⩾0}\{x=a+b:q(a)=-q(b)=r,a\in A,b\in B\}.$$
The null cone is also the intersection of isotropic lines at the origin.

Note: A vector is any element of a vector space over some field in pure mathematics, and it is commonly represented as a coordinate vector. Because they are contravariant with regard to the ambient space, the vectors discussed in this article represent a highly specific instance of this generic concept. The physical understanding underpinning the concept that a vector has "magnitude and direction" is captured by contravariance.