4. Students in a lab group are analyzing the downward motion of a yo-yo as it falls downward while unrolling from its string. The students use a motion detector to construct graphs of distance and velocity of the yo-yo as the yo-yo falls and unrolls. The graphs show that the yo-yo always moves downwards, but that the yo-yo's downward acceleration decreases during its fall. (a) On the axes below, sketch (draw the shapes of) graphs of distance d and downward speed v of the yo-yo as it falls based on the information about the yo-yo's motion stated above. t (b) A student takes the average slope of the velocity vs. time graph to estimate the yo-yo's downward acceleration and finds a value of 21.3 m/s. Should the lab group accept this result? Why or why not? (c) Using rotation principles, explain why the yo-yo's acceleration decreases as it falls and unrolls. (Hint: Think about how the string is wrapped around the yo-yo.)