[填空题]
A person of mass 75 kg 1hhmk.hy5yk7 0+ aj exstands at the center of a rotatin fwt*/t a 5c,el4g1znkg merry-go-round platform ot1z/lfa*kec5 g4 tn, wf radius 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