Q103 / 200 · NEET 2021 · Physics

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 MR2. Then the value of  K is___

  • A
    14
  • B
    78
  • Correct answer
    C
    34
  • D
    18

Solution

mass per unit length of the ring is

λ=M2πR

∴ Mass of remaining ring is M'=λ×34(2πR)

∴  M'=34M

Figure

Moment of inertia of remaining part is

I'=M'R2=34MR2=KMR2

∴K=34

Hence, the correct answer is option: 'C'.

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