Final answer:
The horizontal velocity of a ball in projectile motion is constant and represented by a flat horizontal line on a graph, indicating no change over time. The vertical velocity decreases linearly due to gravity until the ball reaches its peak, after which it becomes negative.
Step-by-step explanation:
The student's question relates to the change in horizontal velocity of a beach ball when thrown through the air, and is best-understood by analyzing projectile motion. In projectile motion, the horizontal velocity is assumed to remain constant if we ignore air resistance. In this case, a student launched a ball with an initial horizontal velocity of 5.00 meters per second. The graph of the ball's horizontal velocity versus time would show a flat horizontal line from the time it was thrown, t = 0, until it hit the ground. This indicates that there is no change in horizontal velocity throughout the flight of the ball, assuming no air resistance. Now, regarding the ball's vertical velocity, the graph would start at an initial vertical velocity and then decrease linearly over time due to gravity's acceleration, which is -9.8 m/s². The vertical velocity will be zero at the peak of the trajectory, and then it becomes negative as the ball falls back down.