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MHT CET202617 April 2026Morning ShiftPhysicsRotational MotionActual

A system of five solid spheres each of mass ' m ' and radius ' r ' are rotating about an axis AA' as shown in figure. Hence the moment of inertia of the system about the axis of rotation AA' is

Options

  1. A6 mr^2
  2. B5 mr^2
  3. C4 mr^2
  4. D3 mr^2

Correct answer

C. 4 mr^2

Step-by-step solution

The system consists of 5 solid spheres, each of mass m and radius r . From the given figure, the axis of rotation AA' passes through the centers of 3 spheres (one at the top and two at the bottom). The moment of inertia of a solid sphere about an axis passing through its center is I_ cm = 2 5 mr^2 . Total moment of inertia for these 3 spheres is: I₁ = 3 2 5 mr^2 = 6 5 mr^2 The remaining 2 spheres are placed such that they touch each other, and the axis AA' passes through their point of contact. Thus, the distance o

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