Question

Two rings `A` (`2m,R`) and `B` (`m,R`) are placed such that these are perpendicular but common center. The `M.I.` of the system about an axis passing through the common center and perpendicular to the plane of `B` is
A. `(1)/(2)mR^(2)`
B. `mR^(2)`
C. `(3)/(2)mR^(2)`
D. `2mR^(2)`

Answer 1

`M.I.` of `A` about its diameter `I_(A)=(1)/(2)xx2mR^(2)=mR^(2)`
`M.I.` of `B` about its axis `I_(B)=mR^(2)`
`I=I_(A)+I_(B)=2mR^(2)`