* A change in speed: Going faster or slower.
* A change in direction: Turning, even if the speed remains constant.
Here are some examples:
* A car speeding up from a stop sign: Its speed increases, so it accelerates.
* A car slowing down to a stop: Its speed decreases, so it accelerates (in this case, deceleration).
* A car turning a corner at constant speed: Its direction changes, so it accelerates.
* A ball thrown straight up: It accelerates due to gravity, slowing down on the way up and speeding up on the way down.
In short, acceleration is any change in a body's motion, whether it's a change in speed, direction, or both.
