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Infinity
Lv 4
Infinity asked in Science & MathematicsPhysics · 8 years ago

Rotational Inertia -- I don't understand how it changes.?

A wheel,with rotational inertia I, mounted on a vertical shaft with negligible ratational inertia, is rotating with angular speed ω 0. A nonrotation wheel with rotational inertia 2I is suddenly dropped onto the same shaft as shown.. The resultant combination of the two wheels and shaft will rotate at:

....

Thanks!

4 Answers

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  • Andrew Smith
    Lv 7
    8 years ago

    Angular momentum is conserved.

    angular momentum is moment of Inertia * angular velocity

    = I w

    After the collision the new moment of inertia is 3I

    So the angular velocity must be w/3

    (w/3) * 3I = I w and angular momentum is conserved

  • pc-5
    Lv 6
    8 years ago

    Use conservation of angular momentum.

    Iw0 = Iw + 2Iw

    Iw0 = 3Iw

    w0 = 3w

    w = w0/3

  • Anonymous
    5 years ago

    So amazed that I found this question already answered! Its like you've read my thoughts!

  • Anonymous
    5 years ago

    Very curious too about the answer to this

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