A child's ball $($a thin hollow uniform sphere$)$ of mass $28\mathrm{.}7$ g and radius $0\mathrm{.}338$ m starts from rest and rolls without slipping down an inclined plane of vertical height $6\mathrm{.}2$ m$.$ What is the angular speed of the sphere at the bottom of the inclined plane? Give your answer in rad$/$s$.$