[填空题]
A person of mass 75 kg stands at the cente3;6ofnd(:3wcfshuc 2 va o.qhr of a rs8mvi9p9q/y xqpws-d piqu04o; (s 8jotating merry-go-round platform of radius 3.0 m and moment of inertia 920q9q/ 4xv u ssio0s-ippwdqpmj y ;988( $kg \cdot m^2$ 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