A satellite of mass m revolves around the earth of radius R at a hight x from its surface. If g is the acceleration due to gravity on the surface of the earth, the orbital speed of the satellite is

Options

A. `gx`
B. `(gR)/(R-x)`
C. `(gR^(2))/(R-x)`
D. `((gR^(2))/(R+x))^(1//2)`

Answer

D

Explanation

For the satellite, the gravitational force provides the necessary centripetal force, i.e.,
`(GM_(e)m)/((R+x)^(2))=(mv_(0)^(2))/((R+x))`