[填空题]
A person of mass 75 kg stands at the center o;xn)b bd v 2 s4 p+hywweo68ccfgia.*4f a rotating merry-go-round plc(0l ,k)h/ax jexsw;xatform of radius 3.0 m and mom ;h)axsx c/j kewx,0(lent 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