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MHT CET202410 May 2024Morning ShiftPhysicsRotational MotionActual

A solid metallic sphere of radius ' R ' having moment of inertia ' I ' about diameter is melted and recast into a solid disc of radius ' r ' of a uniform thickness. The moment of inertia of a disc about an axis passing through its edge and perpendicular to its plane is also equal to ' I '. The ratio r R is

Options

  1. A1 2
  2. B2 5
  3. C2 10
  4. D2 15

Correct answer

D. 2 15

Step-by-step solution

M.I. of the solid sphere about a diameter I = 2 5 MR ^2...(i) M.I. of the disc about an axis through its edge and perpendicular to its plane is array ll & I= 3 2 Mr ^2 ...(ii) & 2 5 MR ^2= 3 2 Mr ^2 & r = 2 15 R array ...[From(i) and (ii)]

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