Fun experiments to disprove Flat Earth

[Stephenk53]

And here is hopefully my last post on this matter (I can't think of the word right now but negatively excited)
Here is 10 ways
https://www.popsci.com/10-ways-you-can-prove-earth-is-round#page-12

 

[Guest812]

How to measure the Earth's radius using a watch, tape measure, and trigonometry:

It is possible to easily see the effects of the Earth's curvature by simply observing the Sun set while you lie on the ground, and afterwards see the sun set again approximately 10 seconds later if you stand up.

In fact, while watching the "double" sunset, anyone can measure the Earth's size with a Meter Stick and a Watch within a matter of a few seconds. For example: suppose while lying on a beach watching the Sun set over a calm ocean, you start a stopwatch just as the top of the Sun disappears. You then stand, elevating your eyes by a height H=1.70 m, and stop the watch when the top of the Sun again disappears. If the elapsed time is t=11.1 s, what is the radius r of Earth?

Knowing nothing more than the height of the eye while lying and standing, and their corresponding "double sunset" elapsed time measurement, knowing the Earth rotates a complete 360 degrees in 24 hours, the Pythagorus right triangle equation, and basic trigonometry, it is possible to fairly accurately calculate the Earth's radius.

If a person wants, a solution to this problem can be found in a book called Fundamentals of Physics by Halliday, Resnick, Walker on page 7 which can be viewed at Amazon's website: http://www.amazon.com/Fundamentals-Physics-Chapters-David-Halliday/dp/0471332356/ref=sr_1_23? s=books&ie=UTF8&qid=1361960056&sr=1-23&keywords=halliday+physics

NOTE: to view page 7 of the book on Amazon's website, I had to first log in, click on the book's "Look Inside" icon, then do a search for the terms "Sun set", and click on the first two search results.

NOTE: I don’t live next to a wide level body of water (i.e. wide level surface), and therefore haven’t taken the above measurements, nor given it much more thought; however I suspect the time difference measurements between Sun sets observed at different heights may vary depending where on Earth, and what time of year the measurements were taken.

 

[Guest812]

About 1,000 years ago, a more accurate calculation of the Earth's radius was made by Al-biruni using a protractor, tape measure, and trigonometry as shown in the below video:

 

[nuuskur]

A thought experiment. If you take off in, say, London and keep flying east. If the Earth was flat, how is it you will get back to London (assuming you keep flying east all the time)?

Any sub-variant will suffice. We know New York lies west from London (general direction). If we fly east, though, at some point we will have passed New York?!

 

[Dr. Courtney]

Wait, it's not flat?

 

[rootone]

Wait, it's not flat?

Yeah, I heard some clever guys discussing that it might be curved in some way, like a donut.

 

[Dr. Courtney]

Yeah, I heard some clever guys discussing that it might be curved in some way, like a donut.

The topological issues are much deeper.

 

[OmCheeto]

Collected some data yesterday, and today I did the maths.

Visually, even at 5 miles, it's obvious.

Guessing that my maths is a bit off (distance of 2.5 miles ≠ 3.8 miles) because of resolution problems.

Regarding the equation in the image:

d = atan((√(z^2+2rz))/r)r
d = how far you have to walk to see something of height z disappear over the horizon.
r = radius of Earth​

Camera was positioned ≈ 0.8 meter above the water line.

 

[ZapperZ]

That's a neat and fun set of observation, @OmCheeto . I've always wanted to do that, but never had the chance.

Now, if only those Flat Earthers actually understand what this all mean.

Zz.

 

[nuuskur]

That's a neat and fun set of observation, @OmCheeto . I've always wanted to do that, but never had the chance.

Now, if only those Flat Earthers actually understand what this all mean.

Zz.

I recall reading or watching a video or something of the sort about a Flat Earther who "debunked" OmCheeto's argument by...climbing higher with the binoculars Then he claimed, he could still see the entire ship even if it's 10 or so miles into the sea (which apparently contradicts this so called math).
I was like "..you don't say" while reading (watching).

 

[sysprog]

Please don't hurt your head over it.

 

[fishspawned]

I am producing a series of 'debates' between myself and my physics 12 students. I feel strongly that their ability to logically conceptualize their ideas and debate them is an important par of the class. Therefore i will argue against groups of four who must argue against a flat earth, moon hoax theories, and other more generic pseudo scientific topics. I will always take the 'pro' side of the quackery. so part of preparation for my own argument is to build up my argument that the Earth is flat. it has involved myself going through a huge range of flat Earth videos. it has been mind numbing.

most of the flat Earth debates have been almost entirely around an argumentation by presenting attacks on a heliocentric solar system and round Earth concept, rather than PROVING the flat Earth one. it avoids suggesting how a flat Earth conceptual model actually accounts for all of the phenomena we observe. Many flat earthers will suggest that gravity itself is not a real thing quite readily without suggesting how alternate theories work BETTER. and this is key - and something all students should internalize. This is not about disproving something. it is about offering an alternate model that will work better than the one already proposed.

so for example, the idea of building a flat Earth model [as suggested earlier in this thread] and asking "OK, do the shadows that the model predicts actually jive with real life observations?"
this is a fantastic idea, which allows for some really fun possibilities. you could have students in different schools around the globe simultaneously measure [well as long as they have sunlight, anyway] and determine the angles they have found. those angles can be used to determine if near proximity sun actually is predicted, or if they suggest parallel lines from a spherical surface. a littel geometry is needed - but fun to play with

 

[Mr Level]

Two more ideas:

Focault pendulum - shows it's the Earth that rotates and not the stars

Direct measurement via surveying. This looks tricky - the Earth curves at about 8 inches per mile. If you had two towers 20 miles apart you could show that each one is 15 feet lower than the other.

A 20 mile distance equals a 266 feet drop in curvature.
https://dizzib.github.io/earth/curve-calc/?d0=20&h0=0&unit=imperial

 

[Vanadium 50]

That is a completely different answer to a completely different question.

 

[YoungPhysicist]

Maybe clips of hurricanes.
Hurricanes won't spin in different directions in different hemispheres if the Earth is flat.

 

[FactChecker]

It would be more fun to offer a $million reward for the person who finds the edge and watch them go around and around. What a GREAT reality/comedy show that would be!

 

[OmCheeto]

It would be more fun to offer a $million reward for the person who finds the edge and watch them go around and around. What a GREAT reality/comedy show that would be!

Brilliant!
Reminds me of the prize James Randi was offering the "psychics".

Prior to Randi's retirement, JREF sponsored the One Million Dollar Paranormal Challenge, which offered a prize of one million dollars US to eligible applicants who could demonstrate evidence of any paranormal, supernatural, or occult power or event under test conditions agreed to by both parties. [ref]​

I have to admit, that every time I see a news article that puts a skewer into their flat Earth ideas, it makes me laugh.
I also entertain myself by trying to imagine what new excuse they will come up with.

For instance, last week someone claimed to have been the first to make a solo trip across Antarctica.
The flat earthers claim that's where the edge of the world is, and that there is a big wall there.
That guy could have made a million dollars just by taking ONE PHOTOGRAPH.
But did he? NO!
Foolish person.

ps. Obviously, NASA paid him two million dollars, not to take a picture of it.

 

[Skeptic Tom]

Take them for a day trip to the beach, or large body of water, say about 10kilometers wide. Get them to look through a good pair of binoculars and ask them if they can see the waves washing up on the shore on the other side. It cannot be done because the curvature of the Earth gets in the way.