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Using expressisions for power and kinetic energy of rotational motion, derive the relation `tau = I alpha`, where letters have their usual meaning. |
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Answer» We know that power in rotational motion, `P = tau omega` ..(i) and `K.E.` of rotation, `E = (1)/(2)I omega^(2)` …(ii) As power=time rate of doing work in rotational motion, and work is stored in the body in the from of `K.E.` `:. P = (d)/(dt) (K.E.` of rotation) `= (d)/(dt) ((1)/(2)I omega^(2)) = (1)/(2)I xx 2 omega((d omega)/(dt))` Using (i), `P = tau omega alpha` or `tau = I alpha`, which is the required relation. |
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