Hi! Im working on this problem:(adsbygoogle = window.adsbygoogle || []).push({});

A solid circular disk has a mass of 1.2 kg and a radius of 0.17 m. Each of three identical thin rods has a mass of 0.16 kg. The rods are attached perpendicularly to the plane of the disk at its outer edge to form a three-legged stool. Find the moment of inertia of the stool with respect to an axis that is perpendicular to the plane of the disk at its center. (Hint: When considering the moment of inertia of each rod, note that all of the mass of each rod is located at the same perpendicular distance from the axis.)

Here is my thinking so far (but im stumped!):

-Moment of Inertia's are additive

- The moment of inertia for the circular disk is (1/2)M*R^2

- I don't know how to get the moment of inertia for the three legs because they dont give me a mass. Im pretty sure the formula is 1/3M*L^2 but I dont know L ??

Thanks for the help.

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# Homework Help: Additive moments of inertia?

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