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27

I live close to Lake Erie and often see scenes like in this picture. Note that the bottom of the cargo ship cannot be seen due to the curvature of the Earth.


20

Related to the Andrea di Biagio answer. Here is a typical flight path for the Beunos Aires-Auckland route. The distance is approximately 10,300 km by the shortest route along a sphere. Direct flights are offered by Air New Zealand and take 11h40m - an average speed of 882 km/h. Looking at the map you present, the distance from Auckland to Buenos Aires looks ...


11

Foucault Pendulum is a great example. The original purpose of this experiment was to prove that earth rotates relative to the stars and not the other way around, yet nevertheless it proves that the earth rotates in a way which contradicts the "flat earth" theorem. This experiment can be easily recreated at home, if you don't live close enough to equator.


9

You need three flat Earth theorists on different continents (or otherwise well separated) all in on a (video) conference call, and have them measure the azimuth and elevation angles of the sun at the same time. The set of angles that they report will be inconsistent with their locations being on a flat disk laid out as in the map in the question. This is a ...


6

Airplanes. Note that dozens of flights cross every ocean and the equator in all directions every day. If the Earth were a disk, it would actually be impossible to do that. For example, if the border of the disk were more or less where the borders of a planisphere are, it would be impossible to cross the Pacific. How would your friend explain how flights ...


5

Can you convince your friend that time zones are for real? If he will believe that it is nighttime in China when it is daytime in the US, then his disk theory can't be correct.


5

There are several factors that may be taken in account, but the more important is the energy used deforming the tire. Suppose a deflated tire. As you move forward and the tire rotates, the part of the tire that is starting to touch the ground has to be deformed (since the tire is flat). You have to use an important amount of energy for that. Note that the ...


5

Consider that the specific heat of water is 4.147 kJ/kg. The specific heat of air is less than 1/4 of that, so for the air to heat you as much as the water, you would have to heat the air to a much higher temperature. That's one reason, along with conduction, that Arctic explorers say that water cools you 30 times faster than air. So it doesn't balance out. ...


5

It is not about momentum. The total momentum is conserved: the fingernail flies in one direction, and you (plus the nail clipper) suffer a recoil to the opposite direction. The thing is that your piece of fingernail has a very small mass compared to your body mass, and the firing speed is actually not so high, so the recoil is negligible. About why the ...


5

If you believe that anyone lives on antarctica at all, or really anywhere south of the antarctic circle, then you can use the "midnight sun" effect, which should not happen in the flat earth theory (because the sun moves around the "antarctica ring" during northern winter). Surveillance cameras will also work for this, if eyewitness accounts are not ...


3

Take an arrow which you put tangent to the earth (assume it to be a perfect sphere). Now, travel around in such a way that 1) you enclose some finite area, 2) do not rotate the arrow locally. Coming back to your starting point you will notice the following: Although you did not rotate your arrow locally, you will end up with an arrow which is rotated ...


3

If the sun is a disk (or sphere) that is a certain distance above the earth, close enough that you get it at different angles above the horizon depending on where you stand, then it has to look like a different size to different people. If it looks the same size, then you cannot explain that it's at a different height above the horizon. See this diagram: ...


2

This sticker is indicating caution when you heat a liquid. Microwave can lead to superheater water which can be dangerous. If your water is superheated, it may not explode/boil over until an object is placed inside the water (e.g. a spoon). One way around this is to place a chop stick or object into the water while it is heating. This will prevent that ...


2

Try https://www.insecam.org/ .Take a flat map of earth and make them go to the cities and watch the light and the online clocks. Nothing but a sphere fits the data. If the sun is going around a disk there would be night almost simultaneously over the flat disk, whereas the cameras will show progressive changes and night for half of their flat earth.


2

There are two factors at play: the first is surface tension, which tends to generalize the action of forces across an area, instead of those forces localizing at one infinitismal point. Second, atmospheric pressure is still in effect. As gravity pulls on the liquid in the pipette, pressure in the bulb diminishes, so external atmospheric pressure pushes ...


2

So steam is caused when you have a supersaturated water vapor that cools and forms large suspended water droplets in the air. This is governed by the kelvin equation which you can read more about here: https://en.wikipedia.org/wiki/Kelvin_equation To get larger water droplets, or in your case a denser looking steam, you have two options: 1. you increase ...


2

Have them pull out their smart phone and open up Google maps and touch the icon to zoom to their current location. Remind them that what they just did is only made possible by satellites in orbit using clocks specially tuned according to general relativity to maintain accurate synchronization with clocks on the surface (i.e., in the smart phone). Welcome ...


1

Pouring anything into the cup adds mass but doesn't add angular momentum. Conservation (plus friction between fluid and cinnamon) of angular momentum requires the new total mass to rotate slower than the original contents.


1

Heat transfer can occur by conduction, by convection, and by radiation. If you consider conduction through the bulk of the cup, the rate of heat transfer is directly proportional to the temperature difference across the material of the cup. As your experiment holds all variables equal except the temperature difference, cup A will lose heat at a faster rate ...


1

We don't harvest waste artificial light, because it would be ridiculously expensive to do so. The energy in sunlight is, at full sun, $1000W/m^2$. That's way higher than any artificial light in normal circumstances. So it's far more economic to position solar panels to optimise collection of daylight, rather than to capture artificial light at night. Any ...


1

Your central heating system doesn't work to keep the house warm: It works to keeps the thermostat warm. If the rest of the house gets warm too, that's just a side effect. If you put a portable electric heater under the thermostat, then the central heat won't have to come on because the electric heater will keep the thermostat plenty warm. But, that ...



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