Rotating a massless rod of length R about the midpoint of the rod with a mass of 2m attached to one end and a mass of m to the other. What is the moment of inertia? My book is terrible at giving good examples, there's nothing similar to this. Do I treat them as two seperate point particles, take the moment of inertia of each around the axis and add them? (2m*(r/2)^2) + (m*(r/2)^2) I'm assuming I can treat them as points, the drawing has the masses as clearly different sized spheres, but says nothing about their radius or anything of that nature. Thanks in advance guys.