Explanation: \(\text{Hints: } v = \sqrt{\frac{gR^2}{R + h}}\) \(\text{Solve: } R = 6400 \, \mathrm{km} = 6.4 \times 10^6 \, \mathrm{m}, \, h = 700 \, \mathrm{km} = 700 \times 10^3 \, \mathrm{m}\) \(\therefore v = \sqrt{\frac{9.8 \times (6.4 \times 10^6)^2}{6.4 \times 10^6 + 700 \times 10^3}} = 7519 \, \mathrm{ms^{-1}}\) \(\text{Ans. (D)}\)