# What is the moment of inertia of a hoop of 6.5Kg and 39cm radius about its normal axis?

$I = 0.98 k g {m}^{2}$
From the definition of moment of inertia $I = \int {r}^{2} \mathrm{dm}$:
consider a small element $\mathrm{dm}$ of the hoop: