Two masses 400 g and 350 g are suspended from the ends of a light string passing over a heavy pulley of radius 2 cm. When released from rest the…

Two masses $\displaystyle 400$ g and $\displaystyle 350$ g are suspended from the ends of a light string passing over a heavy pulley of radius $\displaystyle 2$ cm . When released from rest the heavier mass is observed to fall $\displaystyle 81$ cm in $\displaystyle 9$ s . The rotational inertia of the pulley is $\displaystyle \_\_\_\_$ $\displaystyle \mathrm{kg} . \mathrm{m}^2$. $\displaystyle \left(\mathrm{g}=9.8 \mathrm{~m} / \mathrm{s}^2\right)$