* Acceleration is a change in velocity. Velocity includes both speed (how fast an object is moving) and direction.
* Acceleration can be positive or negative. Positive acceleration means the object is speeding up, while negative acceleration means the object is slowing down (also called deceleration).
* Acceleration can also occur when an object changes direction. Even if the object's speed remains constant, if it changes direction, it is accelerating.
Examples:
* Car speeding up: Positive acceleration.
* Car braking to a stop: Negative acceleration.
* Car turning a corner at constant speed: Acceleration due to a change in direction.
In summary: Acceleration is about a change in velocity, which can involve a change in speed, a change in direction, or both.
