[填空题]
A person of mass 75 kg2 y.(ecb)gxyd stands at thb*p7.0fsn 5/j61 0sp9up wnqr nvoubte center of a rotating merry-go-round platform of radius 3.0 m us usbw v6 p9j5bop/q1n nr*.07n0tpfand 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