[填空题]
A person of mass 75 kg stands at the cent5yj;e zb-7jxh er 0 d d87o cf2jne01loooof a rotating merry-go-round platform of radius 3.0 m andc7d2loono18efd0 0o j 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