[填空题]
A person of mass 75 kg stands at the 9k(yyk m l l;;qd2(zvlcenterklnnbz,u5dh3 c ,m3.b/arlu * of a rotating merry-go-round platform of radunkld5 /bm ra3 zh3,*c nl,u.bius 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