[填空题]
The rings of Saturn are composed org .8mk) )oo7x,0dvhwb1 ug ap(c/kdff chunks of ice that orbit the2 x b8ow.5sa,as ga c2m;z6zye planet. The inner radius of ths8y,;zbw a o 6sm cge2x2z.5aae rings is 73,000 $\mathrm{~km}$ , while the outer radius is 170,000$ \mathrm{~km}$ . Find the period of an orbiting chunk of ice at the inner radius and the period of a chunk at the outer radius. Compare your numbers with Saturn's mean rotation period of 10 hours and 39 minutes. The mass of Saturn is 5.7 $\times 10^{26} \mathrm{~kg}$ .
