Question

Is zero relative velocity
possible? Explain

Answer 1

Yes it is possible .

Answer 2

of course, it is possible that relative velocity is zero. Let's take an example to understand it.

Let A and B two trains arw moving with same speed v in same direction. then, relative velocity of A with respect to B is zero.
$V_{AB}=V_A-V_B=v-v=0$

of course it is true, because when two trains are moving with same speed in same direction then, one train is rest with respect to other , that's why when we travel by train and we observe sometime our train is rest with respect to other train . when both train are moving approximately same speed.