[填空题]
A person of mass 75 kg stands at the center of a rotating merry-gt2lo sw3):o8r8qvz lpe6dv * dof8ns 4o-round ph-s(um*3b xqx f wr2l(latform of radius 3.0 m and moment of inertia (-mu(3 r*bwxsflx2qh 920 $kg \cdot m^2$ The platform rotates without friction with angular velocity 2 $rad/s$ The person walks radially to the edge of the platform. (a) Calculate the angular velocity when the person reaches the edge. $rad/s$ (b) Calculate the rotational kinetic energy of the system of platform plus person before and after the person’s walk.$KE_i$ = J $KE_f$ = J