* Acceleration is the rate of change of velocity. Velocity includes both speed and direction.
* If an object accelerates in the same direction as its motion, its speed increases. Think of a car speeding up.
* If an object accelerates in the opposite direction of its motion, its speed decreases. Think of a car slowing down.
* If an object accelerates perpendicular to its motion, its speed might not change but its direction will change. Think of a car turning a corner at a constant speed.
In short, acceleration directly affects the speed of a moving object.
