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COMEDK · Physics · 8. Rotational Motion

Let \(I_A\) and \(I_B\) be moments of inertia of a body about two axes \(A\) and \(B\), respectively. The axis \(A\) passes through the centre of mass of the body but \(B\) does not, then .

  1. A \(I_A \lt I_B\)
  2. B \(I_A \lt I_B\), whether the axes are parallel or not parallel
  3. C if the axes are parallel \(I_A \lt I_B\)
  4. D if the axes are not parallel \(I_A \geq I_B\)
Verified Solution

Answer & Solution

Correct Answer

(C) if the axes are parallel \(I_A \lt I_B\)

Step-by-step Solution

Detailed explanation

\(I_{\mathrm{CM}}\) is less than \(I\) about any other axis not passing through centre of mass but only when two axes are parallel. \(\Rightarrow \quad I_B=I_A+I_A r^2\) where, \(r\) is the distance between parallel axes. \(\therefore \quad I_A \lt I_B\)