Rotational Motion Question 61

Question: The moment of inertia of a uniform circular disc of radius R and mass M about an axis touching the disc at its diameter and normal to the disc is:

[AIPMT (S) 2006]

Options:

A) MR2

B) 25MR2

C) 32MR2

D) 12MR2

Show Answer

Answer:

Correct Answer: C

Solution:

  • The moment of inertia about an axis passing through centre of mass of disc and perpendicular to its plane is

    ICm=12MR2

    where M is the mass of the disc and R its radius.

    According to theorem of parallel axis, ML of circular disc about an axis touching the disc at its diameter and normal to the disc is

    I=ICM+MR2

    =12MR2+MR2

    =32MR2



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