# How do I calculate the moment of inertia with velocity? [closed]

How do I calculate a total moment of inertia when I have point mass with velocity? It looks like this:

If I understand correctly, firstly I have to find a center of mass. What do I do next?

## closed as off-topic by Norbert Schuch, Daniel Griscom, Gert, JamalS, user36790 Jan 20 '16 at 2:26

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Here's a hint,

We know $I=MR^2$ (considering point mass) from the axis of rotation where $R$ is the perpendicular distance from axis of rotation.

Since each point mass is moving with a constant velocity in the same direction, it means that perpendicular distance from axis of rotation remains same.

So you can calculate moment of inertia of each point mass and add them up.

But the problem is ,it could have been solved if we had known the perpendicular distance of the point mass from the axis of rotation which is near 2a in X-axis.

• I think only one mass is moving, although it's not entirely clear from the statement of the problem. And I don't understand your last paragraph. – garyp Jan 19 '16 at 18:26
• Can you see a point mass near the X coordinate 2a , the problem is we don't the x coordinate of that point mass – Dimenein Jan 20 '16 at 2:15
• Wow. Someone screwed up. – garyp Jan 20 '16 at 15:12