A thin uniform rod of length L, and we need the radius of gyration k about an axis passing through its centre and perpendicular to its length. Formulae: Moment of inertia (M.I.) about the given axis for a uniform rod is: I=‌
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ML2 The radius of gyration k is related to the moment of inertia by I=Mk2 Substituting: ‌Mk2=‌