I tried to get the potential from the potential energy and I get a positive sign for potential...! I cannot find what I did wrong. - Gravitational force is conservative so its work W is symmetrical to the change in potential energy U. - Potential is the work done by gravitational force, per unit mass, to bring a mass from infinity to a certain point P. Initial position of mass: ∞ Final position of mass: point P W = - ΔU W = - (Up - U∞) W = - (-GMm/rp - (-GMm/r∞)) W = - (-GMm/r + 0) W = GMm/r W/m = GM/r Potential = φ = W/m = GM/r It should be negative... Thank you.