[填空题]
A person of mass 75 kg stand 6r :hpk)ao x f-k;j18zece2hms at the c4 x1r r*bw;yoqk zf+w:enter of a rotating merry-go-round platform of radius 3.0 m and moment of iq wro*f;kw+: xrzy4 1bnertia 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