1. The problem statement, all variables and given/known data What is the ratio of inertia of a 5 meter radius disk to that of a 5 meter radius ring? How would this ratio change if the ring were replaced with a since point mass a distance 5 meters from a pivot point? 2. Relevant equations I = mr2 3. The attempt at a solution The wording in this problem seemed a bit funky to me, but going through it, what I think I figured out is that the inertia would be the mass of the disk times 25. However, since it doesn't give me a mass and just asks me to compare the inertia ratio, I'm also guessing that there is something else that separates the inertia of a disk and a "ring." It could just be mass, since a ring doesn't have mass (assuming he's talking about a theoretical ring, just a circle around an axis essentially), and after that, I don't have any more guesses. Any help would be very appreciated! Thanks in advance!