The moment of inertia of a uniform circular disc of radius ' $R$ ' and mass ' $M$ ' about an axis passing…

The moment of inertia of a uniform circular disc of radius ' $R$ ' and mass ' $M$ ' about an axis passing from the edge of the disc and normal to the disc is
  1. $\mathrm{MR}^{2}$
  2. $\frac{1}{2} \mathrm{MR}^{2}$
  3. $\frac{3}{2} \mathrm{MR}^{2}$
  4. $\frac{7}{2} \mathrm{MR}^{2}$

Solution

M.I. of a uniform circular disc of radius 'R' and mass 'M' about an axis passing through C.M. and normal to the disc is
$\mathrm{I}_{\mathrm{C} . \mathrm{M}}=\frac{1}{2} \mathrm{MR}^{2}$


From parallel axis theorem $\mathrm{I}_{\mathrm{T}}=\mathrm{I}_{\mathrm{C} . \mathrm{M} .}+\mathrm{MR}^{2}=\frac{1}{2} \mathrm{MR}^{2}+\mathrm{MR}^{2}=\frac{3}{2} \mathrm{MR}^{2}$

Asked in: JEE Mains - Rotational Motion - Test 1

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