[填空题]
A person of mass 75 oxn 0:2,ubkkidoe/ x 1dxkk h-:f4cm4qv)k8w bdi8 y :lys9c.kg stands at the center of a rotating merry-go-round platform of radius kb.8s vly )ic9dwq8y: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