Consider a small satellite moving in a circular orbit(radius) about a spherical planet(mass).Which expression gives this satellites orbital...

The gravitational acceleration between the satellite of mass m moving arround a spherical plannet of mass M and radius r is given by:

F = GMm/r^2, but this is also the centrepetal force due to the velocity v of the satellite which is mv^2/r

Therefore, mv^2/r = GMm/r^2  or

v =  sqrt(GM/r)  = (GM/r) ^(1/2).