[填空题]
The rings of Saturn are composed of chunks of ice that l vz9 o7g(ree8orbit the planet. The i u 88xzuvs*fv-nner radius of the rings is 73,0xz8s-v u8fvu*00 $\mathrm{~km}$ , 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 $\times 10^{26} \mathrm{~kg}$ .
