Is it possible that the average velocity for some interval may be zero although the average velocity for a shorter interval included in the first interval is not zero?

Explanation

Yes. If a particle moves along a straight line with constant 1 st in one direction say in + x direction for some interval of time `Delta t_(1)` then it everses its direction and moves for another time interval `Delta t_(2)` and reaches the same point then for total interval `Delta t_(1)+Delta t_(2)` the average velocity is zero `( :. (Deltax)/(Deltat)= "O"/(Deltat)=0)`displacement is zero , but for 1st or 2 nd time intervals the average velocity is not zero . Is `(Deltax)/(Deltat)`, the average velocity of the particle during a time interval `vecDeltat` is equal to the slope of the staight line joining initial and final points on the position - time graph.