Final answer:
The yellow tennis ball will continue to move horizontally while the red tennis ball drops vertically.
Step-by-step explanation:
The yellow tennis ball will continue to move horizontally while the red tennis ball drops vertically. This is because the yellow ball has an initial horizontal velocity and no vertical velocity, while the red ball has an initial vertical velocity due to being dropped. The horizontal motion of the yellow ball will not be affected by the vertical motion of the red ball.
Learn more about horizontal and vertical motion