[填空题]
A person of mass 75 kg stands at ty.wh7f ( deec,a7(r brhe c huo :tc)z5zf1 hoyja58 2fcu1cqz :3penter of a rotating merry-go-round platform of radius 3.0 m anqh:a1fo5 ft82hc1z)ozc35j :zpu cu yd 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