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cheechnchong

- 132

- 1

**Rotational Motion on an Axis Problem: Helpppp?**

Problem: Two thin rectangular sheets (0.20 m x 0.40 m) are identical. In the first sheet the axis of rotation lies along the 0.20-m side, and in the second it lies along the 0.40-m side. The same torque is applied to each sheet. The first sheet, starting from rest, reaches its final angular velocity in 8.0 s. How Long does it take for the second sheet, starting from rest, to reach teh same angular velocity?

My Approach: I Didn't setup any equations just yet...kinda confused about how to come up with the TIME!?? I drew the 2 identical rectangles on different axes (on on the 0.40-m side and the other on the 0.20-m side). From the given information, I know that both have equal torque and mass; however, radius I am not sure about since they're on different axis (should i use the moment of inertia I=mr^2 here? to figure the radius). Ok once i have the radius, WHERE do i plug it into find TIME!?

I think I know how to solve it, but it's just a few things i cannot figure from this problem. Thanks!