[填空题]
A person of mass 75 kg psc f +jcp 6lv/qp/g7-stands at the ce,3.;eyd3ot5lsazsrz nter of a rotating merry-go-round platform of radius 3.0 m ar.,3sso5 zz3el;tadynd 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