[填空题]
A person of mass 75 kg stavnc2cu yi1+, rt9(vcd +u1zqjaq7 r6jnds at the center of a rotatingcy8h2kk/n c7kr o7x2wao8 wx16lx,z t merry-go-round platform of radius 3.0 m a1nxr2tk 87lakk7y w c/ ow,cozxh8x 26nd 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