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MHT CET202120 Sep 2021Evening ShiftPhysicsRotational MotionActual

A solid sphere of mass M , radius R has moment of inertia ' I ' about its diameter. It is recast into a disc of thickness ' t ' whose moment of inertia about an axis passing through its edge and perpendicular to its plane remains ' I '. Radius of the disc will be

Options

  1. A4 R 11
  2. B3 R 4
  3. C2 R 15
  4. D2 R 3

Correct answer

C. 2 R 15

Step-by-step solution

For solid sphere, I = 2 5 MR ^2 For disc, I ^ = MR ^ 2 2 + MR ^ 2 = 3 2 MR ^ 2 aligned & I^ =I & 3 2 M R^ 2 = 2 5 M^2 & R^ = 2 15 R aligned

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