When an object has an average velocity but not a constant velocity without acceleration, it means that its velocity changes over time, even though the overall average velocity remains the same. Here are a few examples:
A pendulum swinging back and forth: A pendulum oscillates, changing its velocity as it swings from one side to the other. However, if you consider the average velocity over a complete swing cycle, it will be zero, as the pendulum returns to its starting position.
An object moving in a circular path at a constant speed: When an object moves in a circular path at a constant speed, its velocity is constantly changing. The velocity vector is tangent to the circular path and points in the direction of motion. Although the object's speed remains constant, its velocity changes direction continuously, resulting in a changing velocity.
A ball thrown upwards: When a ball is thrown upwards, it moves against the force of gravity. Initially, its velocity decreases until it reaches the highest point and starts to fall back down. Despite the changing velocity during the upward and downward motion, the average velocity over the entire trajectory might still be constant if the ball returns to its initial position.
Traffic moving through a series of traffic lights: When driving through a series of traffic lights, your car may have to stop and start depending on the signal lights. Your average velocity over the entire journey might be constant, but the car's velocity is not constant as it accelerates and decelerates at each traffic light.
In these examples, the objects have an average velocity that remains the same over time, but their instantaneous velocities change due to varying conditions or forces acting on them.