If two circular discs A and B are of same mass but of radii r and 2r respectively, then the moment of inertia of A is

If two circular discs A and B are of same mass but of radii r and 2r r

1.	If two circular discs A and B are of same mass but of radii r and 2r respectively, then the moment of inertia of A is
Answer» the same as that of B twice that of B four times that of B one-FOURTH that of B Solution :Given, radius of CIRCULAR disc, `A, r_(1)=R` Radius of circular disc B, `r_(2)=2r` For disc A, `I_(A)=mr^(2)`…(i) For disc B, `I_(B)=m(2r)^(2)=4mr^(2)`…(II) Dividing EQ. (i) by Eq. (ii), we get `:. (I_(A))/(I_(B))=(mr^(2))/(4mr^(2))rArr(I_(A))/(I_(B))=(1)/(4)rArr I_(A)=(1)/(4)I_(B)` So, `I_(A)`= one fourth that of B.