plz explain about the above topic

In non-relativistic kinematics, relative velocity is the vector difference between the velocities of two objects, as evaluated in terms of a single coordinate system.

For example, if the velocities of particles A and B are and respectively in terms of a given coordinate system, then the relative velocity of A with respect to B (also called the velocity of A relative to B, , or ) is

.

Conversely, the velocity of B relative to A is

.

The expression "the velocity of A relative to B" is shorthand for "the velocity of A in the coordinate system where B is always at rest".