* Speed tells you how fast an object is moving. It's only concerned with the magnitude (the numerical value).
* Velocity tells you how fast an object is moving *and* in what direction. It includes both magnitude and direction.
Therefore, you can change the velocity of an object without changing its speed by simply changing its direction.
Here are some examples:
* A car driving around a roundabout: The car's speed might be constant, but its velocity is changing because its direction of travel is constantly changing.
* An object in uniform circular motion: The object is moving at a constant speed, but its velocity is constantly changing because its direction of motion is always changing.
* A ball thrown straight up: The ball's speed slows down as it goes up, then increases as it falls down. However, its velocity changes direction from upward to downward at the peak of its flight.
In short: Changing direction changes velocity even if the speed stays the same.
