Other SHM Systems question from JEE Main 2026 (4 Apr, Shift 2)

Answer: (a)

1. Axis A is a tangent in the plane of the disc. About a diameter $I = \frac{MR^2}{4}$; parallel axes: $I_A = \frac{MR^2}{4} + MR^2 = \frac{5MR^2}{4}$.
2. Physical pendulum: $T = 2\pi\sqrt{\frac{I_A}{Mgd}}$ with $d = R$.
3. $T = 2\pi\sqrt{\frac{5MR^2/4}{MgR}} = 2\pi\sqrt{\frac{5R}{4g}}$, answer (a).