[填空题]
A centrifuge rotor rp j-k .iydl:k.otating rkr.s;ilod* id 06gb/ at 10,300 rpm is shut off and is eventually brought uniformly to resisd0*irlgk6d br /o .;t by a frictional torque of 1.2 $m \cdot N$ If the mass of the rotor is 4.80 kg and it can be approximated as a solid cylinder of radius 0.0710 m, through how many revolutions will the rotor turn before coming to rest, $rev$ how long will it take? s