[填空题]
A person of mass 75 kg s+;dcx nku/f,idt 1 )jcwoic,(tands at the center of a rotating merry-go-round platflxiyy2 mzf 3,9orm of radius 3.0 m and momentxmf32 il,yzy9 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