Q.

A uniform solid cylinder with radius R and length L has moment of inertia I1, about the axis of the cylinder. A concentric solid cylinder of radius R'=R2 and length L'=L2 is carved out of the original cylinder. If I2 is the moment of inertia of the carved out portion of the cylinder, then I1I2= _______ .        [2023]


Ans.

(32)

I1=m1R22  I2=m2(R/2)22

I1I2=4m1m2=4·ρπR2ρ·πR24×2I1I2=32