[填空题]
A person of mass 75 kg ./ b*d*roczzk12la kh k(wi3fj::ag f stands at the cr1p7p t m5saje4;:egc enter of a rotating merry-go-round platformrpsm7p4ajgt15 eec: ; of radius 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