[填空题]
A person of mass 75 kg s9v-c7mpdn bua p9cg6n ms5/m2tands at the center of arb2 me3q axz4(;g,l rk rotating merry-go-round platform of radius x 2br 4,3aeg;lkzq(m r3.0 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