Answer:
The vertical velocity increases
Step-by-step explanation:
The motion of the ball is the motion of a projectile, which consists of two independent motions:
- a horizontal motion, with constant velocity
- a vertical motion, with constant acceleration (g=9.8 m/s^2) directed downward
When the ball is travelling downward, its vertical velocity is directed downward. The acceleration is in the same direction (downward), so the vertical velocity is increasing.