A uniform bar has two small balls glued to its ends. The bar is 2.40 m long and with mass 2.70 kg, while the balls each have mass 0.600 kg and can be treated as point masses. Find the moment of inertia of this combination about an axis perpendicular to the bar through its center. Find the moment of inertia of this combination about an axis perpendicular to the bar through one of the balls. Find the moment of inertia of this combination about an axis parallel to the bar through both balls.

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anonymous · Answer

Let's use the parallel axis theorem, which is expressed as$$I = \bar I + mr^2$$where $\bar I$ is the moment of inertia through the CG, m is the mass at the ends, and r is the distance from the CG to the masses. You can find expressions for moment of interas here: http://en.wikipedia.org/wiki/List_of_moments_of_inertia