Verified Solution • 2025–26 Session moderate

QJEEM25Phb35d: JEE Main 2025 Physics - Class 11 JEEM25Phb35d Solution: A uniform circular disc of radius ' and mass ' is rotating…

A uniform circular disc of radius ' R′\mathrm{R}^{\prime} and mass ' M′\mathrm{M}^{\prime} is rotating about an axis perpendicular to its plane and passing through its centre. A small circular part of radius R/2R / 2 is removed from the original disc as shown in the figure. Find the moment of inertia of the remaining part of the original disc about the axis as given above.

JEE Main 2025 (Online) 22nd January Morning Shift Physics - Rotational Motion Question 10 English

Multiple Choice Options

  • A 1732MR2\frac{17}{32} \mathrm{MR}^2
  • B 1332MR2\frac{13}{32} \mathrm{MR}^2
  • C 932MR2\frac{9}{32} \mathrm{MR}^2
  • D 732MR2\frac{7}{32} \mathrm{MR}^2

Step-by-Step Verified Solution

amp;I=MR22−[M4(R2)22+M4(R2)2]amp;I=1332MR2\begin{aligned}& \mathrm{I}=\frac{\mathrm{MR}^2}{2}-\left[\frac{\frac{\mathrm{M}}{4}\left(\frac{\mathrm{R}}{2}\right)^2}{2}+\frac{\mathrm{M}}{4}\left(\frac{\mathrm{R}}{2}\right)^2\right] \\& \mathrm{I}=\frac{13}{32} \mathrm{MR}^2\end{aligned}

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