[填空题]
A person of mass 75 kg stands at the center of a rotating merrj02u+7 vsxbbd0b8xp h; qpb2 eyqv b 57nnb)iy2krvzn4es t/9(-go-round platform of radius 3.0 m and moment of in 9k2zvynvi)s nqbb/ 4(7e5 tnrertia 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