NEET2021PhysicsRotational MotionActual
From a circular ring of mass M and radius R an arc corresponding to a 90 ° sector is removed. The moment of inertia of the remaining part of the ring about an axis passing through the centre of the ring and perpendicular to the plane of the ring is K times M R 2 . Then the value of K is___
Options
- A1 4
- B7 8
- C3 4
- D1 8
Correct answer
C. 3 4
Step-by-step solution
mass per unit length of the ring is λ = M 2 π R ∴ Mass of remaining ring is M ' = λ × 3 4 ( 2 π R ) ∴     M ' = 3 4 M Moment of inertia of remaining part is I ' = M ' R 2 = 3 4 M R 2 = K M R 2 ∴ K = 3 4