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NEETPhysicsRotational Motion

Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R. Assertion A: Moment of inertia of a circular disc of mass M and radius R about X , Y axes (passing through its plane) and Z-axis which is perpendicular to its plane were found to be I x , I y and I z , respectively. The respective radii of gyration about all the three axes will be the same. Reason R: A rigid body mak

Options

  1. ABoth A and R are correct but R is not the correct explanation of A.
  2. BA is not correct but R is correct.
  3. CA is correct but R is not correct.
  4. DBoth A and R are correct and R is the correct explanation of A.

Correct answer

B. A is not correct but R is correct.

Step-by-step solution

I z = I x + I y (using perpendicular axis theorem) and I = m k 2 ( K : radius of gyration) so m K z 2 = m K x 2 + m K y 2 K z 2 = K x 2 + K y 2 So radius of gyration about axes x , y and z will not be same, hence assertion A is not correct reason R is correct statement (property of a rigid body).

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