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A thin horizontal disc is rotating about a vertical axis passing through its fixed centre O. Its angular momentum is L_A and L_B computed about points A and B, respectively, with OB=2× OA. The value of (L_A)/(L_B) is :

Asked in Re-NEET 2026 · Angular momentum of a rigid body

• (1) 1/4
• (2) 1/2
• (3) 1
• (4) 2

Step-by-step solution

Why the other options are wrong

• (1) Takes the angular momentum about a point to vary as the square of that point's distance from O, as if applying the parallel-axis theorem; nothing is moving about a new axis.
• (2) Takes the angular momentum about a point to be proportional to that point's distance from O.
• (4) The inverse of the distance ratio; the angular momentum does not depend on where the reference point lies.

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