This blew my mind. I had to check the math.

The math is incorrect. Adding 10 m to the rope length does not add 10 m of height from the radius of the circle. It is a cool mathematical trick but it is not acc

That seems intuitively so wrong to my brain

Lost me at the earth is a perfect ball. Maybe for your thought experiment. Otherwise:

Then why if I let my belt out one notch it’s still tight?

The Earth is not a perfect sphere.

Earth is an oblate spheroid. Not a “perfect ball”. Not really necessary for the point he’s making… just pointing out an interesting difference.

Here’s a simpler version I use… Q: a rope goes around the globe at ground level. How much extra rope is needed if we lift it 1 meter off the ground everywhere? A: about 6 meters. (2x pi). Calculations: circumference of earth = (radius)x 2 pi It’s a big number, but that doesn’t matter. Adding a meter in height adds 1 m to the radius. new circumference = (radius+1m) x 2 pi So new circumference has an additional 1m x 2 pi = approx 6 meters.

I disagree with this, the earth is not a perfect sphere, it is flattened at the poles, so a rope stretched around the poles rather than the equator would be a far different size.

Another way to think about these kinds of things is to turn it into a square to make visualization easier. The difference between a square and a circle is less than an order of magnitude. Square earth has 4 sides R. Add 10m total rope and you get sides R+2.5, for a 1.25m gap.

“Earth is a perfect ball”? I believe the mountain begs to differ

@grok but isn’t it he adding 10m directly to the diameter, not the radius? If the 10m was added to the rope length circumnavigating earth, wouldn’t that be added to the entire diameter around earth, and the radius or the new gap would be minuscule?

False. He did not solve for “h.” He falsely states Rprime minus R is h, but this is not true. An ant couldn’t crawl under the new rope.

The "Earth isn't a perfect sphere" folks are incapable of abstract thinking. The point isn't the oblateness, its that 10m of extra rope makes a non-intuitive difference.

This math is wrong. You need to know the radius of the earth; then calculate the circumference; then add 10 meters to the circumference, then back-calculate the radius for that new circumference.

The earth is NOT a perfect ball which makes the rest of video bullshit.

Was have a really good, confident, self respecting day before this tweet happened to me.

The problem as stated was adding 10 meters to the circumference, not the radius. It’s all incorrect after that error

If the earth was a cube shape and you added 10 meters to the rope, there would be a 1.25 meter gap, similar to the sphere. Easier to visualize and make sense of when dealing with square shape. 10/8 is the formula.

The circumference of the equator is approximately 40,000,000 m in length, if you tied a rope that length end to end and wrapped it around the equator and then added 10 m to it, you would only be adding 0.00000025 of the original length to itself. That barely does anything.

This is fucking stupid. The earth is not a perfect sphere and is contantly changing shape. It is an ellipse. 🥴 this guy is a fucking dweeb

This is what happens when you get AI to do your math. It is so wrong. What a dumb cunt.

The Earth is a vastly better approximation of a sphere than a cue ball (billiard ball) when scaled down to the same size.

Can’t believe people are falling for this

No 100% won't work. Math may tell you this is true, but try it and it won't work.

you lost me at “imagine a rope…”

I am convinced this kind of math is witchcraft.

If ever a post was in need of verification, this is it. @grok does the math check out?

Aspirin anyone?

If you want to be able to sleep tonight, try this. Take a circumference of 1,000,010 and calculate its radius. Write down the answer. Then take a circumference of 1,000,000 and calculate its radius. => logic crushes intuition. You’re welcome.

I was like no way let me do the math the way I want to do it...1.59 meters he is right

A very imperfect globe though - by certain accounts.

10 meters of circumference is a lot different than adding 10 meters of radius

This is a fun one to pair with “you have a 1 mile length of rail that is fixed to ground at end points only. On hot day the rail expands by one foot causing it to arc. How high is the peak of the arc? Is it high enough that it would be an issue for a train?”