Here's why:
* Gravity is the only force acting: Once the ball is in the air, the only force acting on it is gravity.
* Constant acceleration: Gravity causes a constant acceleration, approximately 9.8 m/s² downwards, regardless of the ball's velocity.
* Direction matters: The acceleration is always downwards, even when the ball is moving upwards.
Important Note: This assumes negligible air resistance. In reality, air resistance will slightly affect the acceleration, but for most everyday scenarios, the acceleration due to gravity is the dominant factor.
