Here's why:
* Velocity is a vector quantity: This means it has both magnitude (speed) and direction.
* Direction matters: When we choose a positive direction (e.g., right, upward), the opposite direction becomes negative (e.g., left, downward).
* Average velocity considers displacement: It's calculated by dividing the total displacement by the total time. Displacement is the overall change in position, taking into account both distance and direction.
Example:
Imagine a car moving 10 meters to the left (negative direction) in 2 seconds.
* Displacement: -10 meters (negative because it's to the left)
* Time: 2 seconds
* Average velocity: (-10 meters) / (2 seconds) = -5 meters/second
The negative sign indicates that the car's average velocity is in the opposite direction of the chosen positive direction.
In short, a negative average velocity doesn't mean the object is moving "backward" in an absolute sense. It simply means it's moving in the direction we've defined as negative.
