Write the relation between instantaneous velocity and relative velocity for uniform motion.

For an object moving with uniform motion,the velocity remains constant over time.
Let $v_A$ be the velocity of object $A$ and $v_B$ be the velocity of object $B$.
The relative velocity of object $A$ with respect to object $B$ is defined as $v_{AB} = v_A - v_B$.
Since the motion is uniform,the instantaneous velocity at any time $t$ is equal to the average velocity.
Therefore,the instantaneous relative velocity $v_{rel}(t)$ is given by $v_{rel}(t) = v_A(t) - v_B(t)$,which remains constant for all $t$ in uniform motion.