>>12979667The G constant is an approximation. If you have a problem like "find equation that predicts a situation" you come up with all variables that play a role in the situation (this is based on what you think plays a role) you then verify this by leaving everything constant other than one variable for each variable. Then you get a graph for each variable and then you see from the graph how the variable and the end function are connected. After you have done this with all variables you have your equation.
For instance, there is a force between two masses, now it seems like mass is involved, since an apple is attracted to the earth but not to me or another apple (at least the force between to apes is too weak to move them) and since the mass of one object plays a role the other does as well, then obviously the radius should play a role since we aren't attracted to the moon as much as the earth from the earth even if accounted for mass.
The next step is to take to objects, one of variable mass and then measure the force between them, if you plot force and mass you will see that the plot is a straight line, thus you know: F(m) = C*m where C is the other variables, you also know that's true for the other mass, thus F(M, m) = C*M*m. Now you do it with variable radius and you will find that the plot is of the function 1/x^2, thus you know F(M, m, r) = C*M*m/r^2. Now we have exhausted all variables so the C in that case is a constant we call G, thus we arrived at our equation. Now you just hope that that equation can predict any such situation accurately
