[填空题]
A person of mass 75 kg stands at the cent p(iyxnzh)rb;jpa:kt,r i1b3d5l16py 4r 8 z zer of a rotating merry-go-round plx :qf* tk* ur-/irvng-atform of radius rx-gvtr- *k /unqfi:* 3.0 m and moment of inertia 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