



 
Drop/mile is a bad measure of curvature because it isn't a ratio. If we approximate the Earth as a sphere, half the distance means (for short distances) about 1/4 the drop. You can measure curvature in degrees per mile  how fast does the direction of vertical change as you move? (The answer is about 0.00145 degree per mile.) So if you drive 100 miles in a straight line, the direction of "up" changes by about 1/7 degree. That's quite measurable with fairly simple instruments! Good Hunting!  


Math Central is supported by the University of Regina and The Pacific Institute for the Mathematical Sciences. 