A rod of length L rotate about an axis passing through its centre and normal to its length with an angular velocity ω. If A is the cross-section and D is the density of material of rod. Find its rotational K.E. : 

(1 / 24) AL³Dω²  

Moment of inertia for rod = I

I = (ML² / 12)

K.E. = (1/2)Iω² 

  = (1/2) × (ML2 / 12)ω2 

  = [(ML2ω2) / (24)]

Density : D = [(mass) / (volume)]

D = (M/V) = (M / A.L)

M = D.A.L

KE = [(DAL³ω²) / (24)]