At what velocity in (km/s) should a body be projected horizontally at a height of 30 km from the ground so that it becomes the satellite of the earth? neglect air friction. (radius of earth is $6370 \;Km$)

Question

\[(a)\;7.6 \quad (b)\;7.9 \quad (c)\;9.8 \quad (d)\;11.2\]