Question

what is relative velocity​

Answer 1

The relative velocity {\displaystyle {\vec {v}}_{B\mid A}} {\displaystyle {\vec {v}}_{B\mid A}} (also {\displaystyle {\vec {v}}_{BA}} {\displaystyle {\vec {v}}_{BA}} or {\displaystyle {\vec {v}}_{B\operatorname {rel} A}} {\displaystyle {\vec {v}}_{B\operatorname {rel} A}}) is the velocity of an object or observer B in the rest frame of another object or observer A.

Classical mechanics