How to Convince Your Flat-Earth Friends the World Is Round

You can see that now we have a proper triangle with the hypotenuse equal to the distance from the observer’s eyes to the heart of the Earth (R + h), with the different two sides being simply R and the distance to the horizon (s). Using the Pythagorean theorem, we will remedy for s:

Now we simply want to plug in our values for R and h to get a distance of 4,657 meters, or about 2.89 miles. Of course, if you happen to improve your distance from the floor (h), then it’s also possible to see farther. But standing on the shore of a lake, it solely wants to be 3 miles extensive and you will not find a way to see the different shore. Yes, it is as a result of the Earth is spherical.

Swinging a Pendulum

This second experiment is a little bit tough to arrange, however you do not want a large lake. You want to get a mass hanging on the finish of a string and let that mass swing forwards and backwards—sure, that might be a easy pendulum. However, if you happen to have been to fastidiously let it go (with out giving it any round movement), the pendulum would not simply swing forwards and backwards. Instead, it will slowly change the course that it swings. This is commonly known as a Foucault pendulum (named after Leo Foucault).

Why does this occur? Let’s take this to the excessive case so that it’s going to make extra sense. Imagine you will have a mass hanging from a degree precisely at the North Pole (assuming there may be nonetheless some ice there for you to stand on). As the pendulum swings forwards and backwards, the Earth under it’s going to rotate (as a result of the rotation of the Earth is what causes night time and day). Here’s an animation of what that might form of appear like (not in actual time).

The pendulum simply swings forwards and backwards, nevertheless it’s the Earth that rotates beneath it. This makes the pendulum seem to change instructions because it rotates, and it will take half a day for the pendulum to once more swing in its unique course (as seen from the North Pole). A full cycle would take someday.

But wait! This would not show the Earth is spherical. Maybe it simply exhibits that the flat Earth rotates like a file on a file participant. OK, truthful, however how about this? If you are taking that very same pendulum to the South Pole it’s going to additionally rotate—however in the wrong way, since you’ll be standing in Antarctica, fully the other way up with respect to the North Pole pendulum.

But you do not have to go to the North or South Pole to do that experiment. You can do it at dwelling. The pendulum will once more swing in several instructions as the Earth rotates, however it’s going to take longer than half a day to return to its unique course, and the time will rely in your latitude.