Question

When does the average velocity become zero?

Answer 1

Average velocity of a particle is 0 when its displacement is 0 as velocity= displacement/time.
But during the path that the body covers (distance) it never comes to rest but keeps moving and changing direction in order to come back to the same point. This way the velocity is never 0. Even when it is changing its direction, even at that instant the instantaneous velocity is not 0.