[theDentist]

What is the mathematical formulae for gravity?

[inquest]

I can't write it out in proper mathematical form, but I know that the gravity from any given point of mass is directly proportional to that mass, and inversely proportional to the square of the distance from it.

When dealing with a uniform shell of mass (and planets can be thought of as just a bunch of concentric uniform shells of mass), the gravity, for all points outside the shell, is the same as it would be if all the mass were concentrated at the center.

[brownsfan]

I was somewhat in error. Density does matter in that the more dense an object is the smaller the radius. This website has a good treatment of the subject.

http://www.geocities.com/nickemarkov/ExpansionAndGravitation.html

[mikrofon]

What is the mathematical formulae for gravity?

G^mn = -(8pG/c²)T^mn
ds² = c²(1-2MG/c²r)dt² - dr²/(1-2MG/c²r) - r²(dq²+sin²qdf²).
dt = (1-2MG/c²r)^1/2dt
dt1/dt2 = (1-2MG/c²r1)^1/2/(1-2MG/c²r2)^1/2
rc = 2MG/c²
dt1/dt2 = (1-MG/c²R)(1+MG/c²(R+h)) =  1 - (MG/c²)[1/R - 1/(R+h)]
1-dt1/dt2 = (MG/c²)(h/R²)
(n2-n1)/n2 = (MG/c²)(h/R²)