Why Are Manhole Covers ALWAYS Round?

Описание: Here are the key takeaways from the video:

Safety Hazard of Square Covers: If manhole covers were square or rectangular, they could be lethal. Because the diagonal of a square or rectangle is longer than its sides, a square cover turned or tilted slightly can fall vertically straight through its own hole.
The Advantage of Round Covers: A circle is the unique shape that maintains an identical diameter from every single angle. As a result, a round manhole cover can never fall into the hole, regardless of how it is rotated or turned.