[填空题]
A person of mass 75 kg stands at thxm/4.(k b;ez)nu tu 2j+gt i6mecnpp/e center of a j .uip05wrt4e rotating merry-go-round platform of radius 3.0 m and mtju5pe4 rw .0ioment 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