[填空题]
A person of mass 75 kg stands at the center of9k)r o7iy o3 ttoff.jb1z0k70wxa zf; a rotating merry-go-round platd0v5yqif*( h zv xb..vn/sso 7form of radius 3.0 m and moment of ine5fi hds.vvso yb(*nxv /q0. z7rtia 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