A satellite orbits the earth at a height equal to the radius of the earth. Find its orbital speed in $\mathrm{km}/\mathrm{s}$. ($G=6.67\times {10}^{-11} {\mathrm{Nm}}^2{\mathrm{kg}}^{-2},$mass of earth $M=6\times {10}^{24 }\mathrm{kg}$, radius of Earth $R=6400 \mathrm{km}$) (Answer up-to three places of decimal)

A satellite orbits the earth at a height equal to the radius of the earth. Find its period of revolution in hours(write the value to the nearest integer).

($G=6.67\times {10}^{-11} {\mathrm{Nm}}^2{\mathrm{kg}}^{-2},$mass of earth $M=6\times {10}^{24 }\mathrm{kg}$, radius of Earth $R=6400 \mathrm{km}$) 

Calculate the escape velocity(in $\mathrm{km} {\mathrm{s}}^{-1}$) in kilometres of a body from the Earth's surface. ($g=9.8 \mathrm{m} {\mathrm{s}}^{-2}, R=6400 \mathrm{km}$)