Final answer:
Acceleration is a vector quantity defined as the change in velocity over time, which means it includes changes in magnitude (speed) or direction, or both.
Step-by-step explanation:
Acceleration as a Vector
Acceleration is the change in velocity over time. Given information in physics is often categorized as either a vector or a scalar quantity. Acceleration, specifically, is a vector. This is because acceleration is in the same direction as the change in velocity, denoted as Δv.
Since velocity itself is a vector - it has both magnitude and direction - it can change in these aspects. Acceleration is, therefore, a change in either speed or direction, or both. For example, if you are traveling in a car and turn a corner at a constant speed, you are still accelerating because the direction of velocity is changing.
The SI unit for acceleration is meters per second squared (m/s²), which takes into account both the magnitude (how much the velocity increases or decreases in speed) and the direction of the change.