Question:
A yo-yo consists of two massive uniform disks of radius R connected by a thin axle. As shown in the figure, a thick string is wrapped many times around the axle, so that the end of the string is initially a distance R from the axle. Then, the end of the string is held in place and the yo-yo is dropped from rest. Assume that energy losses are negligible, and that the string has negligible mass and always remains vertical. Below, we show a cross-section of the yo-yo partway through its descent. Between the moment the yo-yo is released and the moment the string completely unwinds, which of the following is true regarding the yo-yo's acceleration?
(A) It is always zero.
(B) It points downward, but decreases in magnitude over time.
(C) It points downward and has constant magnitude.
(D) It points downward, but increases in magnitude over time.
(E) None of the above.
*Note: This problem references figure(s): `image_question/F=MA_2024_25_1.png`*