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While watching the first 4 seconds of driving at 745 km/h is ludicrous from any angle wondered

1)If we knew the curvature of the earth in a "flat" desert, what would be the speed of the car?

2)Assuming we don't know the curvature of the earth, how long would it take for the car to go around the earth ( assuming a "flat" desert all the way travelling on a great arc)?

Using my ninja pause skills it seemed it took 2 seconds from the time the car appeared ( as a dot ) in horizon to the time it passed by the camera, although 2 second window of observation seems to lead to a great error in overall estimates, using the 745 as the value for 1 and 2 the error of human observation could be calculated (?)

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You need to know the height of the camera to know how far the horizon is on a flat surface. –  Ron Maimon Nov 13 '11 at 6:14
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Additionally, one cannot assume that the car popped over the horizon in the video, as the point at which it appears could have simply been the point where its angular diameter fills a single pixel of the camera. –  Richard Terrett Nov 13 '11 at 7:37
    
@RichardTerrett : true, it seems there is nothing more can be done –  Arjang Nov 14 '11 at 6:38
    
well, if you know the height of the car, even assuming the camera is at equal height can you give a good estimation. However, my guess is that there might be refraction atmospheric effects that will make the car visible much later than pure straight line optics would predict –  lurscher Nov 14 '11 at 12:31
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I hate to say "it depends", but it depends on how far away you can see the other car. If it's the size of an ant, not very far. If it's the size of a planet, really far. (As a pilot, this is not academic. You train yourself to inspect the sky for specs that appear not to be moving, because any other aircraft on a collision course with you looks exactly like that.) Also those awesome trains in France appear out of nowhere and flash past you. –  Mike Dunlavey Dec 13 '11 at 22:55
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