OpenStax College Physics for AP® Courses, Chapter 19, Problem 28 (Test Prep for AP® Courses)

This is College Physics Answers with Shaun Dychko. This question asks which of these pictures most closely resembles a gravitational field between two equal masses? Well, if we imagine that we have a positive charge— in this picture here say— a positive charge would be attracted to this mass, it would also be attracted to this mass and if a positive charge is put here in the middle, it will be attracted to neither because it will be pulled with an equal force in opposite directions. So this is the picture that most represents how gravity would act you know, this positive charge could be analogous to some mass and this would be another mass and they would be attracted towards each other and if you put the mass in the middle, it would be attracted equally in both directions and so therefore there will be no net force on it and whereas in this picture here, we have attraction always to this negative charge here but repulsion from this charge and with gravity, there can never be a repulsion and I guess you could say in this picture here there could also be repulsion if you had a negative charge introduced, it would be repelled and so of course the analogy between this electric field and gravity is not perfect but certainly this picture here is even less perfect than this one because in this picture, we have different behaviors depending on which charge we are close to and gravity is always an attraction and the behavior is always the same, there's no such thing as a positive gravity or negative gravity it's just gravity and there's always attraction. So this picture here [19.15] is the one most resembling a gravitational field.