# [Rotational Inertia, Angular Velocity] problem without given masses.

1. Nov 26, 2006

### Alpha Russ Omega

Hello:

I seem to be stuck on this one problem: "A meter stick is suspended vertically at a pivot point 0.26 meters from the top end. It is rotated on the pivot until it is horizontal and then released from rest. What will be its maximum angular velocity (in radians per second)?"

So I figured this problem might involve Rotational Inertia: $$I=\sum_i m_{i} r_{i}^2$$

Would I also need to find torque? (I'm getting confused on how the problem does not give me the mass of the meter stick.) Am I using the right formula?

Any help would be appreciated.

2. Nov 26, 2006

### radou

You need to use energy conservation. If the angular velocity is maximal, what does that tell you about rotational kinetic energy? Further on, what does that tell you about potential energy?

3. Nov 27, 2006

### Alpha Russ Omega

Aha! You were dead on right about the energy conservation. Thanks for your help. :-)

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