[单选题]
A satellite is in a low circular orbit a: 1v nwbl jb4dp;+g(mbbus12 mbout the Earth (i.e.z0fwwis,3 swyhh3( 0i, it just skims the surface of the Earth). What is the speed of the satellite? (The mean radius of the0s i3zww3hyh,(siw0 f Earth is $6.38 \times 10^{6} \; m$.)
