Solve this in detail.

48.    A geo - stationary satellite is orbiting around earth at height of 30,000 km in circular orbit. The radius of the earth is taken as 6000 km. The geo - stationary satellite comes back to its position after one revolution is exactly 24 hours. Let the acceleration due to gravity (g) be 10 m/s² and mass of satellite be 1000 kg; calculate the work done in 12 hours when moving under gravitational force .

$$\begin{gathered} \left(1\right) 3.6\mathrm{\pi } \times {10}^{14} \mathrm{J} \left(2\right) 2\mathrm{\pi } \times 7.2\mathrm{\pi } \times {10}^{14} \mathrm{J} \\ \left(3\right) 1.8\mathrm{\pi } \times {10}^{14} \mathrm{J} \left(4\right) \mathrm{Zero} \mathrm{J} \end{gathered}$$

          
                                                                                                                                              (Stage-2, 2013)