Acceleration is the rate of change of velocity. If the velocity of an object is constant, it means that the object is moving at a steady speed in a straight line without changing its direction. In such a case, the acceleration is zero because there is no change in velocity.
Acceleration is a vector quantity, meaning it has both magnitude and direction. When an object's velocity is constant, it implies that there is no change in speed or direction, which means there is no change in velocity over time. Since acceleration measures the change in velocity per unit of time, if there is no change in velocity, the acceleration is zero.
In summary, if an object's velocity remains constant, it implies that there is no acceleration because there is no change in velocity. Acceleration only occurs when there is a change in velocity, either in magnitude (speed) or direction.