A uniform circular disc has moment of inertia I about a diameter. Find its moment of inertia about a perpendicular axis passing through a point on its rim, in units of I.
Physics · Mixed Chapter
JEE Main Practice

Question

A uniform circular disc has moment of inertia I about a diameter. Find its moment of inertia about a perpendicular axis passing through a point on its rim, in units of I.

G1 Physics · Accepted Answer

Step 1: About a diameter I=(1/4)MR². By the perpendicular-axis theorem Icentre,z=(1/2)MR²=2I. Step 2: Move the perpendicular axis from centre to rim (distance R): Irim=Icentre,z+MR². Step 3: MR²=4I, so Irim=2I+4I=6I. Step 4: Multiplier=6.