It is impossible to drop a round lid into a smaller round hole.
It is because round is the only shape that if turned or flipped over, it still retains the same length across its center. If you used a square, rectangle, triangle, hexagon or any other shaped lid, it could be rotated and fall into the hole.
This can't happen with the round shape.
And I have worked for the phone company for the last 22 years, yes it is a pain to get a rectangular lid that weighs 100 lbs, out of a 6 foot deep hole by yourself.
Two more correct answersA round cover can be moved by rolling it on its edge.A round cover contains less metal than a same-sized cover of any other shape.
actually a round manhole cover isint the only shape that would work a reulux triangle would work too and square manholes would puncture tires
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Manhole covers are round because that is the only shape that will not fall in on itself. Having a round cover with a lip, there is no way the cover can fall or be forced into the hole it covers.
wala
because for any person to get inside a manhole, you would think it was shaped like a round circle.
The reason that manhole covers are round, and not square, is because a square cover could, when placed at the right angle, fall through the square hole in the ground. A circle, however, is the same diameter no matter where you measure it, and it cannot fir through a hole the same size and shape, no matter how hard anyone tried.
A circular cover is the only shape that can fit the hole no matter which way you drop it, but can't possibly fall through the hole no matter which way you drop it.