A solid disk and a hollow disk with the same mass and diameter are released together (from rest) to roll down an incline. The solid disk reaches the bottom first. From this information we can say that the angular acceleration was
A) larger for the hollow disk.
B) larger for the solid disk.
C) the same for both disks.
D) impossible to know without a measurement of time.

Question

Quizplus · Accepted Answer

The solid disk has more mass concentrated at its center compared to the hollow disk, which has most of its mass distributed at the outer edges. This means that the solid disk has a larger moment of inertia (resistance to rotational motion). Since both disks have the same diameter and are released from rest at the same time, the solid disk must undergo less angular acceleration in order to reach the bottom of the incline first. Therefore, the angular acceleration of the solid disk is larger than that of the hollow disk.

A Solid Disk and a Hollow Disk with the Same