Thank you bobpursley.
In question 2, if sea level is 3963 miles from the center of the earth can I change the equation to figure out the weight of a 100 pound weight at lea level by doing something like this?
100=sqrt C/3963^2 ?
No. if you are trying to find the weight of a 100# object at sea lavel, you already have the answer: 100 lb.
The weight of a 100 pound (@ sea level) weight at OTHER distances R from the center of the earth is
W = 100 * (3963/R)^2
In terms of altitude h above sea level, that is
W = 100*[3963/(3963 + h)]^2