Q.

The moment of inertia of a square loop made of four uniform solid cylinders, each having radius R and length L (R<L) about an axis passing through the mid points of opposite sides, is ______. (Take the mass of the entire loop as M).             [2026]

1 38MR2+16ML2  
2 38MR2+712ML2  
3 34MR2+712ML2  
4 34MR2+16ML2  

Ans.

(1)

Inet=2(I1+I2)

=2(M'R24+M'212)+2(M'R22+M'(2)2)

=M'R22+M'R26+M'R2+M'22

=3M'R22+2M'23

Given masses M'=M4

So, I=3(M/4)R22+2(M/4)23

I=38MR2+M26