Rita is a ball girl during Tamara’s match that she is losing. When Rita rolls the ball along the horizontal surface of the court, the ball’s velocity will remain constant. When Tamara drops the ball in preparation for a serve, the ball will accelerate downwards and cover a greater vertical distance each second.
A ball served horizontally will hit the ground at the same time as a ball dropped at the same time from the same location.
Ex: Rita and Tamara both try to underhand serve from the baseline at the same time. The beauty of the underhand serve is that the ball never touches the ground. Rita hits the ball, but Tamara somehow misses. When the balls land on the ground, they will hit at the same time.