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I was given a question of 2 masses m_a and m_b whos centres of L distance apart and are connected by a massless rod (so it kind of looks like a dumb-bell). Each ball through its centre has an axis perpendicular to the rod (axiz a and b respectively) and each has a moment of inertia, I_a and I_b respectively. And it is also fiven that the ratio of I_a to I_b equals three.

Okay I worked out the ratio of the masses of the two balls which was the first part of the question and that came out okay, and then the second part looked way to simple and I can't seem to dig up another answer:

b) Find d_a, the distance from ball A to the system's center of mass (Express in terms of L, length of the rod)

is it just L/2 or is it acutally more complicated than this?

Can someone help me out ? Thank you!!!

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# Homework Help: Centre of mass - is this right?

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