[填空题]
A person of mass 75 kg stands at thy fiyj 4kh*0rzlwq9i-9j eaq6 0yc44e e center of a rotating m;2 e xs2d;:d pzqus 6nk;h2cazerry-go-round platform of radius 3.0 qpu;c 6:d2h;2xas;kdz zs2 enm 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