Here's the breakdown:
* Acceleration is the rate of change of an object's velocity.
* Velocity has both speed (how fast something is moving) and direction.
Therefore, an object can be accelerating in these ways:
* Speeding up: This is the most common way people think of acceleration. The object's speed increases.
* Slowing down: This is called deceleration, and it's also a type of acceleration. The object's speed decreases.
* Changing direction: Even if an object maintains a constant speed, if its direction changes, it is accelerating. Think of a car going around a curve.
In summary: Acceleration describes any change in velocity, whether it's a change in speed, direction, or both.
