Hi, I was attempting to work through this question. Anyways, I was working from a graph, so the radius 2.5 cm, the two of them collided, it was an inelastic collision as the two objects did part ways, so how do I find the centre of gravity? I attempted to calculate it... but if someone could help me out? The masses were 500g and 500g. So for x and y, would I do: Xcg = (500)(0.025) + (500)(1.5)(0.025) / 1000 ? Ycg = (500)(0.025) + (500)(0.025) / 100 ? That's what I was thinking but I'm not entirely sure. After this, I also have to find the momentum of the centre of gravity... so for that, I need the masses and the speed. Even though the objects didn't stick together, would I add the masses when solving for the momentum at the centre of mass? I was reading on the internet and it said: "The center of mass velocity of a system of particles is the average velocity of all the particles weighted relative to their mass" but what I'm confused about is, do I add all the velocities... like the velocities of both the masses before and after the collision? So I'd have 4 velocities? But I'd only add the masses twice right? So it would be the velocities / 1000 g Could someone really help me. Please.