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> Math Challenge -- Flat Earth Debunk

Xarzu
post Sep 12 2017, 11:48 PM, updated 2w ago

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How much would time pass between watching the sun set from ground level and then watching it set again from the top of a sky scraper?

I heard once that this could be done using one of the towers of the World Trade Center. So I assume one could also do this using the Sears / Willis Tower in Chicago. Someone also told me that the world's tallest tower in Dubai is so huge that the local weather broadcast tells of two times for sunset. One time is for the observed sunset at ground level and another time is for the observed sunset from the observation deck near to the top of the tower.

unfortunately, I have recently gotten involved in a debate with someone who believes or claims to believe that the earth is flat and he has challenged me for proofs. I gave him some observations that any one can do, but that did not seem to be good enough for him. He wanted the mathematical predictions of an event and then a demonstration that showed that reality matches the mathematics.

Well, my math skills are a bit rusty on this sort of level since I have been out of college. Although I could probably do this, I figure it would be a greater ease for me to just ask one of the math majors or grad students that frequent online mathematics forums for the equations. So I think what I will do is list my ideas one at a time in this mathematical forum. And now, here is the first one.

The rapper B.O.B. has come out saying that he thinks the earth is flat. Neil Tyson gave him a reply and PBS offered an Op Ed piece explaining some simple tests anyone can do to prove the earth is round. One of them was to lay on the beach on your back and with your head pointed towards the sun set (do this on the pacific coast of course. The moment you see the sun set, immediately stand up and you can see the sun set again -- or so says the op ed piece from PBS. I have herd that something similar can be done with large buildings. If you watch the sun set on the ground level, (let's say from the point of view of a 6ft 4 man. Or some measured eye level from the ground) and then you take an elevator to the top floor, you will be able to see the sun set a second time.

The problem is this, if you know all of the variables, how long would it take to see the sun set a second time.

I hope I have posed this question well enough. Let me know if you have any questions. After this one is answered, I have at least one more question I will start in a second thread.-->

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badai
post Sep 13 2017, 12:27 PM

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adoi where have you been for the past 5000 years? even form 5 student can answer this.

time = height / speed of the sun relative to earth

you can ignore the curvature because the earth is too big compare to whatever tallest building you are on.

now go google what is the speed of the sun relative to earth
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badai
post Sep 13 2017, 04:41 PM

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sorry, not the speed of the sun relative to earth.

speed of the sun as seen from the earth, which is circumference of earth / 1 day, about 0.46383101851851851851851851851852 m/s
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WongGei
post Sep 13 2017, 05:34 PM

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Check this page, horizon,
https://en.wikipedia.org/wiki/Horizon.
This is the place where the sun set.
- For an observer standing on the ground with h = 1.70 metres (5 ft 7 in), the horizon is at a distance of 4.7 kilometres (2.9 mi).
- For an observer standing on the ground with h = 2 metres (6 ft 7 in), the horizon is at a distance of 5 kilometres (3.1 mi).
- For an observer standing on a hill or tower of 100 metres (330 ft) in height, the horizon is at a distance of 36 kilometres (22 mi).
- For an observer standing at the top of the Burj Khalifa (828 metres (2,717 ft) in height), the horizon is at a distance of 103 kilometres (64 mi).

Then what we need is take the distance between 64mi - 5mi, 59mi.

https://www.scientificamerican.com/article/...-the-earth-mov/
From the page, we know that the speed of earth self rotation is about 1000mi per hour

60/1000 = 0.06hr = 3.6min

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Eventless
post Sep 13 2017, 07:10 PM

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https://en.wikipedia.org/wiki/Earth
QUOTE
Mean radius 6371.0 km

1 complete rotation is 24 hours.
Circumference at equator(2piR)=2*3.142*6371=40,035.364km
Rotational speed at equator=40,035.364/24=1,668.14km/h

https://en.wikipedia.org/wiki/Latitude
Different latitudes will result in different circumference so the speed will vary according to latitude.

Radius at 60 degree North/South=6371*cos 60=6371*0.5=3185.5km
Circumference at 60 degree North/South=2*3.142*3185.5=20,017.682km
Rotational speed at 60 degree North/South=20,017.682/24=834.07km/h
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RaymondReddington
post Sep 13 2017, 07:41 PM

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You're all replying to a spambot.
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skizzo75
post Sep 13 2017, 07:43 PM

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The earth is donut shape
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