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JEE Main20204 Sep 2020Evening ShiftPhysicsRotational MotionActual

Consider two uniform discs of the same thickness and different radii R 1 = R and R 2 = α R made of the same material. If the ratio of their moments of inertia I 1 and I 2 , respectively, about their axes is I 1 : I 2 = 1 : 16 then the value of α is :

Options

  1. A2 2
  2. B2
  3. C2
  4. D4

Correct answer

C. 2

Step-by-step solution

Moment of inertia of disc is given by I = MR 2 2 = ρ πR 2 t R 2 2 I   α   R 4 I 2 I 1 = R 2 R 1 4 16 1 = α 4 α = 2

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