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A uniform rod of mass m and length lo is rotating with a constant angular speed ω about a vertical axis passing through its point of suspension. The moment of inertia of the rod about the axis of rotation if it makes an angle θ to the vertical (axis of rotation) is

a
ml02sin2θ12
b
ml02sin2θ6
c
2ml02sin2θ3
d
ml02sin2θ3

detailed solution

Correct option is D

We can observe each and every element of rod in rotating with different radius about the axis of rotationTake an elementary mass dm of the rod.dm = ml0dlThe moment of inertia of the elementary mass is given as dl = (dm)r2The moment of interita of the rod =  I = ∫dI  ⇒I = ∫r2dmSubstituting r = 1 sin θ and dm = ml0.dl, we obtainI = ∫(l2sin2θ)ml0dI = msin2θl0∫0l0l2dl = ml023l0sin3θ⇒I = ml02sin2θ3

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