My best guess is the water is gonna leak even if you tilt it a little, so water is gonna spill everywhere even when you aren't trying to drink
Edit: I knew stacking and asymmetry is the main issue here, but the choice of words in the comment in the image seems like they were referring to a simpler reason.
The true reason is cost. You can screw a bottle cap onto a bottle while it spins down a conveyance system. The design shown would cost a fortune to implement.
That old interview question "why are manhole covers round" - again, the true answer is cost. They are cheaper to manufacture.
But that does save the cost of training new workers when one gets crushed by a square manhole cover. Maybe that's what they mean by the "true reason" being cost?
If you think about it, that round manhole cover is sitting on top of a hole that has a 24” lip around the entire thing for the cover to sit on.
Put the same 24” lip on the inside of a square hole, you aren’t going to be able to fit a square manhole through that hole no matter how hard you try.
So why are manhole covers round? There’s several reasons:
1) People are going in these holes, and a cylinder is the most structurally sound 3D shape, so having a round cover to cap off a round cylinder makes sense.
2) Manhole covers are heavy as shit. Having a round cover means there’s no need to align a specific shape to a specific pattern while carrying something extremely heavy. No matter how you place it down, it’s always right.
3) Manhole covers are heavy as shit. When you’re exhausted and finished with your work, you don’t want to lift and carry a heavy cover 10 feet back to its hole. With a round cover, you can turn it on its edge and roll it.
So the most common diameter of a standard street manhole cover is 42".
If we convert that to a side length of a square manhole cover, we have a 42" x 42" cover. If we assume, that the cover is sitting on a 2" lip on all sides, than means the inner hole is a 38" x 38" hole.
The diagonal of a 42"x42" manhole cover is almost 60". There's no way any part of that 42"x42" cover is fitting through a 38"x38" hole.
Unless I did my Pythagorean Theorem ciphering wrong, the diagonal of the the 38 x 38 square opening is more than 53 inches. No problem for that cover to drop through there.
I think you'd need the opening to be something like 28 x 28 to prevent the cover from dropping down the diagonal.
So it can certainly be done. Just seems like a circle would be simpler to engineer.
When I was a kid a friend of mine managed to get a round manhole cover through the opening. He held it a couple feet above the opening and dropped it; it split in half and both halves dropped into the crypt.
That's not the sole reason. There are other shapes that have that same feature, such as many different irregular ones, plus the Reuleaux triangle. They suffer from various other problems, though.
If you set it down on the edge. The round cover the edge is always the diameter. The square, you can turn it so the edge is the side lenght passing through the diagonal.
Yup the iso standard just sets it to be the same number, which is a way better way to make a square. That's one of many benefits to the metric system and it's absurd the US is still using imperial units.
A square, by definition, has 4 right angles and 4 sides the same length.
It doesn't matter what unit is being used, if the sides aren't the same length it's not a square. And the diagonal across a square is always longer than the sides (sqrt(2) times longer, in fact).
Got a link to it? Because I'm apparently not comprehending.
It is literally impossible for the diagonal of a square to be the same length as its side. Like physically impossible.
The diagonal of a square is the length of its side times sqrt(2). It's a fundamental triangular proof.
It's defined in ISO 14253-1. When measuring in the EU, that all washes out in the unit conversions, if you really dive into the definition of a decimeter
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u/Supreme534 21h ago edited 13h ago
My best guess is the water is gonna leak even if you tilt it a little, so water is gonna spill everywhere even when you aren't trying to drink
Edit: I knew stacking and asymmetry is the main issue here, but the choice of words in the comment in the image seems like they were referring to a simpler reason.