Q. The ratio of the radius of gyration of a thin uniform disc about an axis passing through it centre and normal to its plane to the radius of gyration of the disc about its diameter is:
A) $1 : \sqrt{2}$
B) 2 : 1
C) $\sqrt{2} : 1$
D) 4 : 1
Explanation
[Solution] $I_{centre} = MR^2/2$ gives $k_1 = R/\sqrt{2}$; $I_{diameter} = MR^2/4$ gives $k_2 = R/2$. Ratio $= \sqrt{2} : 1$. Answer (3).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.