Question
Physics Question on System of Particles & Rotational Motion
A circular disc X of radius R is made from an iron pole of thickness t, and another disc Y of radius 4R is made from an iron plate of thickness 4t. then the relation between the moment of inertia IX and IY is
A
Iy=32Ix
B
Iy=16Ix
C
Iy=32Ix
D
Iy=64Ix
Answer
Iy=64Ix
Explanation
Solution
If t is the thickness and R is the radius of the disc, then mass =pR2t? ?= density of the material of the disc. Moment of inertia of disc X, Ix=21πR4tρ...(i) Moment of inertia of disc Y, Iy=32πR4tρ...(ii) From equation (i) and (ii) Iy=64Ix