2006-06-25 06:05:11 · 6 answers · asked by Anonymous in Social Science ➔ Other - Social Science
The most common answer is simply that a round manhole cover can't fall into the hole it covers. Heavy, round manhole covers are easier for one person to move by standing it on end and rolling. Also, you don't have to "align" a manhole cover to it's hole ... any orientation will do.
2006-06-25 06:11:57 · answer #1 · answered by Gray Matter 5 · 4⤊ 1⤋
Round covers can be removed and moved easily.
2006-06-25 06:51:25 · answer #2 · answered by Ifeelso706 3 · 0⤊ 0⤋
they are round because if they accidentally get set down vertical in their hole, they won't fall in. a square will just fall straight through, but a circle, because it bulges, will not just slip straight onto a person's head below.
2006-06-25 06:09:23 · answer #3 · answered by mystique_365 2 · 0⤊ 0⤋
So they don't fall in the hole.
A square or rectangle could fall in the hole if they are turned on end, circles do not.
2006-06-25 06:09:50 · answer #4 · answered by Left the building 7 · 0⤊ 0⤋
I know this one!!! So that when being removed or replaced, they do not fall into the abyss- below. There is a geometric equation that can be located as to the technical reasoning.
2006-06-25 06:09:03 · answer #5 · answered by ••Mott•• 6 · 0⤊ 0⤋
they cant fall through the hole-if square they would
2006-06-25 06:09:00 · answer #6 · answered by Joe 5 · 0⤊ 0⤋