Final answer:
The answer to whether a position vs. time graph of an object that is speeding up is a straight line is false. Objects that are accelerating have a curved position vs. time graph, not a straight one.
Step-by-step explanation:
The student's question relates to the interpretation of motion graphs in physics. More specifically, whether a position vs. time graph of an object that is speeding up is a straight line. The answer is false. Objects that are speeding up will have a curved position vs. time graph, where the curvature indicates acceleration. If the graph were a straight line, it would represent constant speed, not acceleration. For the scenario involving the two baseballs, more information is required to determine the exact nature of the motion, but if either baseball is speeding up or slowing down, this would be represented by a curved line on a position vs. time graph.
In the context of a marathon or any prolonged physical activity, understanding these principles about motion is important for both strategies in pacing and athletic training.