Answer :
Final answer:
The ball's velocity is -0.8 m/s.
Explanation:
The initial speed of the ball is given as 9 m/s and it is thrown downward. We can assume that the acceleration due to gravity, which is approximately 9.8 m/s², will act in the opposite direction to the initial velocity. Because the ball is thrown downward, the direction of its velocity will be negative. Therefore, the ball's velocity can be calculated by subtracting the acceleration due to gravity from the initial velocity:
Velocity = Initial Velocity - Acceleration Due to Gravity = 9 m/s - 9.8 m/s² = -0.8 m/s
Learn more about Ball's velocity when thrown downward here:
https://brainly.com/question/24234100