[填空题]
A person of mass 75 kgk4ggq4hmxvk )2,q 9 b1 z9vttp stands aflt1gu .jalj)4c.x .st the center of a rotating merry-go-round platform of radius 3.0 m andjal cj.)s..4t gulxf1 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