* Constant: The object could be moving at a constant velocity. This means it's moving at a steady speed in a straight line.
* Changing: The object could be at a point where its velocity is changing direction, even though its acceleration is momentarily zero. Imagine a ball thrown straight up in the air. At the peak of its trajectory, its acceleration due to gravity is still present, but its velocity is zero for a brief moment before it starts falling back down.
In summary: Zero acceleration at an instant doesn't necessarily mean zero velocity. It means the *change* in velocity at that moment is zero.
