* Acceleration is a change in velocity. Velocity has two components: speed (how fast) and direction (which way).
* Constant speed doesn't mean constant velocity. If an object is changing direction, even if its speed remains the same, its velocity is changing. This means it's accelerating.
Examples:
* A car driving in a circle at a constant speed: The car's speed might be 50 mph, but because its direction is constantly changing, it's accelerating.
* A ball thrown straight up: As the ball goes up, its speed decreases until it momentarily stops at the highest point. Then, it falls back down, increasing speed. Throughout this entire motion, the ball is accelerating due to the force of gravity.
Key takeaway: Acceleration is about *changes in velocity*, not just changes in speed. If an object is changing direction, it's accelerating.
