Earth's radius?

Question

How do you determine the radius of the earth using only a stopwatch?

Answer 1

if you were on a satellite (international space station) with a known altitude and a known relative ground speed, you could determine the time it took to make one lap and determine circumference and radius of such orbit and deduce radius of earth by subtracting altitude.

Answer 2

I assume I'm restricted to staying in one place.  If I can move a substantial distance then the problem is trivial.

Measuring my lattitude is easy enough if you're patient (the angle of the sun at local apparent noon on the equinox--or you could use polaris at night).  And if you know the date, you could correct for that.  Then I suppose I could use the transit time of a fixed object from horizon to horizon to figure out how far below vertical the horizon is.  Knowing my height of eye plus knowing my lattitude plus the angle of the horizon should give me a reasonable cut at the curvature.  That'll work at sea if you have flat horizons.  It gets dicey if the land has any contour whatsoever.

If you could see the shadow of the earth during a lunar eclipse, you could probably use that somehow.

Answer 3

I don't think its possible.

Answer 4

The earth isn't a perfect sphere, but it ranges from 6,356.750 km to 6,378.135 km (≈3,949.901 — 3,963.189 mi), which are the polar radius and the equatorial radius, respectively.

Answer 5

well its by focusing on one star and timing the amount of time it takes to appear again in the same place in a 24 hr period and doing a math formula to work it out.

Answer 6

Incidentally, if you actually conduct the experiment described in the link provided by marwa, you'll end up with an answer that is about 15 percent too large, because of atmospheric refraction.

Better do it over a calm ocean, too.

Answer 7

determining the radius of the earth using a stopwatch is possible

It's on this link

http://spiff.rit.edu/classes/phys240/hom...