Here's why:
* Acceleration is the rate of change of velocity.
* Velocity is a vector quantity, meaning it has both magnitude (speed) and direction.
* Positive acceleration means the velocity is increasing in the positive direction. This means the object is moving faster in the same direction.
Example:
Imagine a car driving down a straight road. If the car's speedometer reading is increasing, it means the car is accelerating. If the car is accelerating in the same direction it's already moving, its speed is increasing.
