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JEE Main20209 Jan 2020Morning ShiftPhysicsRotational MotionActual

Three solid spheres each of mass m and diameter d are stuck together such that the lines connecting the centres form an equilateral triangle of side of length d . The ratio I 0 I A of moment of inertia I 0 of the system about an axis passing the centroid and about center of any of the spheres I A and perpendicular to the plane of the triangle is:

Options

  1. A13 23
  2. B15 13
  3. C23 13
  4. D13 15

Correct answer

A. 13 23

Step-by-step solution

M.I about O = 3 2 5 M d 2 2 + M d 3 2 = 13 10 M d 2 M.I about A = 2 2 5 M d 2 2 + M d 2 + 2 5 M d 2 2 = 23 10 M d 2 Now ratio = 13 23

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