Question

what is relative motion ? please explain briefly

Answer 1

Relative motion is the calculation of the motion of an object with regard to some other moving object. Thus, the motion is not calculated with reference to the earth, but is the velocity of the object in reference to the other moving object as if it were in a static state.

Answer 2

motion of any object with respect to another object is called relative motion.
in which we assume one particle is motion with respect to another particle
example earth motions with respect to sun