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NEET Physics Rotational Motion 2025 NEET 2025

NEET Physics Question (2025) — Solution

Question

A sphere of radius R is cut from a larger solid sphere of radius 2 R as shown in the figure. The ratio of the moment of inertia of the smaller sphere to that of the rest part of the sphere about the Y-axis is:

Options

  1. A. 7 8
  2. B. 7 40
  3. C. 7 57
  4. D. 7 64

Answer

C. 7 57

Step-by-step solution

aligned & I _1= 2 5 M (2 R )^2 \\ & I _2= 2 5 mr ^2+ md ^2 \\ & = 2 5 ( M 8 ) R ^2+ M 8 ( R )^2 \\ & = 7 MR ^2 40 \\ & I = I _1- I _2= 8 MR ^2 5 - 7 MR ^2 40 = 57 40 MR ^2 aligned I _2 I _1 = 7 57

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