[填空题]
A person of mass 75 73g6 cnnqp bt3kg s;x ;7/p rec:qgd:ov9 y.-u uz*onhpvytands at the center of a rotating merry-go-round platform of radius gz .op*cxrovyv-u/ed;9 :pqhu:ny7;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