Re: GPS Trip Mileage
Posted by Harold Ericsson on March 12, 2003 at 17:17:40:
In Reply to: GPS Trip Mileage posted by LeRoy Johnson on March 12, 2003 at 15:27:41:
I believe it important to remember the following: Suppose that the earth is a sphere of radius 3963 miles. If you are at a point P on the earth's surface and move tangent to the surface a distance of 1 mile then you can form a right angled triangel. Using the theorem of Pythagoras a2 = 39632 + 12 = 15705370 and thus a = 3963.000126 miles. Thus your position is 3963.000126 - 3963 = 0.000126 miles above the surface of the earth. 0.000126 miles = 12*5280*0.000126 = 7.98 inches. Hence the earth's surface curves at approximately 8 inches per mile.