[填空题]
A person of mass 75 kg stands at tncd*z e:c3xx e6k+ v/q tl/,fxhpqgn pb:1agfw4ej +v .lr /05he center of a rotating merry-go-round platform of radius 3.0 .j1hlebq f50 :4/gpg v apwn+rm 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