MDMD(5)----Chap 15 Questions

[Tom Stanton]

>>MDMD(5)----QUESTIONS
>>158.7 "The attraction of Mountains" If anyone could explain to a
>>mostly (very) lay audience how gravitational mass could in theory
>>have altered the Plumb-lines?
>
>That is what gravity does: masses attract masses.  In this case, that
>of the mountain and earth on one side, versus just the earth on the
>other side, leaving a small net force on any mass caught in between.
>-Matthew P Wiener (weemba at sagi.wistar.upenn.edu)

Most examples of gravity assume a featureless sphere. If you start
getting serious, you do need to account for mountains and other
features (such as the fact Earth is not a sphere but somewhat
pear shaped -- oblate spheriod I think).

There is a US Geological Survey map set that contains what 
I still think is one of the coolest maps I've ever seen: a detailed charting
of "gravitational variances" across this great land of ours. Never knew
anyone charted that kind of detail...