[填空题]
A person of mass 75 kg0c0pz+x z(a -lewfctb:4uwq1 ss8 ox3k yy0:x fs/2 vpcmoh3s hp 5k3fa -/u.ostands at the center of a rotating merry-go-round platform of r sfu/ 2c/ppkh33o-.o 5fhsvamadius 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