* Acceleration is a change in velocity. Velocity is a vector quantity, meaning it has both magnitude (speed) and direction.
* Changing direction means changing velocity. Even if the speed remains the same, a change in direction means the object's velocity vector is changing.
* Any change in velocity, even just the direction, constitutes acceleration.
Think of it this way:
* Constant speed, straight line: No acceleration.
* Constant speed, circular path: Acceleration. The object is constantly changing direction, even though its speed is constant.
* Speeding up: Acceleration (in the direction of motion).
* Slowing down: Acceleration (in the opposite direction of motion).
Key takeaway: Acceleration is about changes in velocity, and those changes can involve both speed and direction.
