A celestial body m At the central celestial body M From infinity Uniform velocity When moving to point A of a certain position, External force (to make m Uniform velocity Sports, m There must also be work done by an external force that is opposite to gravity Is gravitational potential energy 。 If the infinite distance is the zero potential energy point of gravitational potential energy, then the gravitational potential energy expression mean 。 Among them, G by Gravitational constant ， r It is the distance between body and mind in two days, M and m Is the mass value of two celestial bodies 。 hold m In the process of pulling from infinity to A, M And m The space between two is decreasing, and the gravitational force and external force are increasing, which are variable forces. To deal with the problem of variable force work, integration is needed.
Gravitation/external force distance diagram when moving from infinity (potential energy zero) to point A Set point A and M Centroid distance 。 First pay attention to micro elements, then think about them as a whole, we can get [1] 
