JEE Main20257 Apr 2025Evening ShiftPhysicsRotational MotionActual
M and R be the mass and radius of a disc. A small disc of radius R / 3 is removed from the bigger disc as shown in figure. The moment of inertia of remaining part of bigger disc about an axis AB passing through the centre O and perpendicular to the plane of disc is 4 x M R^2 . The value of x is ________.
Correct answer
0
Step-by-step solution
Without cavity I ₁= MR ^2 2 aligned Mass of removed disc = & M R ^2 ( R 3 )^2 & = ( M 9 ) aligned M.I. of removed disc I₂= M 9 ( R 3 )^2 2 + M 9 ( 2 R 3 )^2 aligned & = MR ^2 18 & I = I ₁- I ₂= MR ^2 2 - MR ^2 18 = 4 MR ^2 9 & ( n =9) aligned