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JEE Main 2022 (25 Jun, Shift 2) · Moment of Inertia & Radius of Gyration

Moment of Inertia & Radius of Gyration question from JEE Main 2022 (25 Jun, Shift 2)

Q116JEE Main 2022 · 25 JUN · SHIFT 2Medium

Moment of Inertia & Radius of Gyration

Moment of Inertia (M.I.) of four bodies having same mass 'M' and radius '2R' are as follows: I1 = M.I. of solid sphere about its diameter

I2 = M.I. of solid cylinder about its axis

I3 = M.I. of solid circular disc about its diameter

I4 = M.I. of thin circular ring about its diameter

If 2(I2 + I3) + I4 = x. I1, then the value of x will be __________.

Numerical answer type. Work it out, then open the answer.

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Answer: 5

  1. Radius 2R2R, so r2=4R2r^2 = 4R^2.
  2. I1=25M(4R2)=85MR2I_1 = \frac{2}{5}M(4R^2) = \frac{8}{5}MR^2, I2=12M(4R2)=2MR2I_2 = \frac{1}{2}M(4R^2) = 2MR^2
  3. I3=14M(4R2)=MR2I_3 = \frac{1}{4}M(4R^2) = MR^2, I4=12M(4R2)=2MR2I_4 = \frac{1}{2}M(4R^2) = 2MR^2
  4. 2(I2+I3)+I4=6MR2+2MR2=8MR2=x⋅85MR22(I_2 + I_3) + I_4 = 6MR^2 + 2MR^2 = 8MR^2 = x \cdot \frac{8}{5}MR^2
  5. So x=5x = 5.
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