Thie 51-page paper (Gravity and Its Relation to Electrostatic ans Magnetic Force by Scott F. Sibley) (PowerPoint Gravity Summary and GRAV-G-Blog3 – SFSibley in Word pdf) includes a table of contents, tables (including Supplemental Tables 1 and 2, SFSibley in Excel) and graphs, and a 1-page abstract. Simple equations help explain how results were obtained. By analysis of the interaction between secondary electrical charge within and between units of mass, an equation for G that is verifiable is constructed. A quantum unit of secondary electrical charge is a component of that equation, and this charge can be calculated separately from a derivative equation involving the square of the speed of light that proves the validity of the equation and the assumptions underlying it. An explanation for each of the constant factors in the equation for G is presented, including the weighted average mass number to atomic weight ratio (R) of the Milky Way Galaxy (RMW) as a proxy for that of the universe. Five predetermined physical constants only are used as factors to calculate G to nearly 6 significant figures, almost identical to the value determined experimentally. The probability of calculating G so accurately by chance is extremely low, and to calculate the speed of light squared also, by chance, based on one factor in the equation for G, is even less likely. For such a calculation to be coincidental or fabricated in some way is virtually impossible. This successful calculation of G and the linkage to the speed of light demonstrates the applicability of the weighted average mass number to atomic weight ratio of the universe to all bodies of mass, as a factor in G in a gravitational context, independent of the composition of those bodies and independent of their location in the universe. The implication of this calculation is that gravity is composition dependent, but a change in G requires a change in the proportions of elements in the universe. Gravity is also net attractive, meaning that gravity has a repulsive component. The discovery that G is essentially electrical and based on a quantum unit of charge is corroborated by characteristics of natural and electromagnetism; is consistent with quantum field theory because it involves the interaction of quantum electrical fields to produce quantum secondary charge; and leads to solutions to problems in other areas of geophysics.