A remote sensing satellite of the earth revolves in a circular orbit at a height of $0.25 \times10^6~\text{m}$ above the surface of the earth. If Earth’s radius is $6.38\times10^6~\text{m}$ and $g=9.8~\text{ms}^{-2},$ then the orbital speed of the satellite is:
1. $7.76~\text{kms}^{-1}$
2. $8.56~\text{kms}^{-1}$
3. $9.13~\text{kms}^{-1}$
4. $6.67~\text{kms}^{-1}$