Q.

The ratio of the radius of gyration of a thin uniform disc about an axis passing through its centre and normal to its plane to the radius of gyration of the disc about its diameter is  [2022]
 

1 2:1  
2 2:1  
3 4:1  
4 1:2  

Ans.

(2)

The radius of gyration of a thin uniform disc about an axis passing through its centre and normal to its plane is,

    k=R2                                                    ...(i)

Radius of gyration of disc about its diameter is k'=R2                ...(ii)

Then, kk'=R2R2=2:1