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Units And Measurement

Question
CBSEENPH11017590

A solid sphere and hollow shell of same mass have same moment of inertia about their diameters. What is the ratio of their diameters? 

Solution
Let Rs and Rb be the radii of solid sphere and hollow sphere respectively. Since solid sphere and hollow sphere have same moment of inertia,
therefore space space space 2 over 3 MR subscript straight h squared equals 2 over 5 MR subscript straight s squared space

rightwards double arrow space space space straight R subscript straight s squared over Rh squared equals 5 over 3 space

rightwards double arrow space space space space straight R subscript straight s over straight R subscript straight h equals square root of 5 over 3 end root 
This is the required ratio of their diameters.