[填空题]
A person of mass 75 kg stands a5tcv h,o0 9ye -p/aojit1ot xtj-2y2w 4ku, w 0 t2gke-g1ofhbk the center of a rotating merry-go-round platformbkwf je4o-w 0t2tghkx1o g ,22ky1 -ut of radius 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