[填空题]
A person of mass 75 kg stands at the center om hlhpx/)cm3w661gw(rla5ccd ov v;2f a rotatine.ja tqs-q)l6)w7fpj g merry-go-round platform of radiuswj)p) 6e -7.jq ftalsq 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