 The gravitational potential energy of two particles of mass "M" and "m" separated by a distance "r" is
The gravitational potential (specific energy) of the two bodies is
where formula_51 is the reduced mass.The work done against gravity by moving an infinitesimal mass from point A with formula_52 to point B with formula_53 is formula_54 and the work done going back the other way is formula_55 so that the total work done in moving from A to B and returning to A is
If the potential is redefined at A to be formula_57 and the potential at B to be formula_58, where formula_59 is a constant (i.e.formula_59 can be any number, positive or negative, but it must be the same at A as it is at B) then the work done going from A to B is
as before.