[填空题]
A person of mass 75 kg stands at the center-ptwx wqxi5ws(/ wd c/d2/nk2 of a rukm21 6./pw2z tbhofh/jye2k otating merry-go-round platform of radius 3.0 m and momeneh .2kybw2 2zfh/m1pt/jku6o t 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