man-hole covers: the approx, three foot diameter steel plates seen in the road. typically for a city worker to enter the underground drainage system.
2006-06-15 20:23:17 · 14 answers · asked by spike 2 in Education & Reference ➔ Trivia
Because when they open them they have an edge lip around them and they won't fall through to the bottom if they can't lift them all the way up and they slip or spin in any direction. You do that with any other shape like a square, triangle, etc and it spins a little it will fall through even with a lip.
And they are solid steel to handle the weight of vehicle.
2006-06-15 20:32:46 · answer #1 · answered by careercollegestudent69 4 · 2⤊ 1⤋
1) A round cover cannot fall into the hole accidentally. 2) It is easier to remove a cover that is round. 3) It is easier to move a cover for some distance if it is round. Also, to be politcally correct, should the name be changed to person-hole cover?? LOL.
2016-03-27 05:22:35 · answer #2 · answered by Anonymous · 0⤊ 0⤋
The reason most manhole covers are circular is that the round cover cannot fall into its own hole (the maximum diagonal distance is the same as the radius, unlike rectangular covers where the diagonal distance is greater than the maximum length or width).
2006-06-15 20:25:26 · answer #3 · answered by ♥Hina♥ 4 · 0⤊ 0⤋
Manhole covers are round so that they would not fall into the hole. If it were a sqaure, the cover could fall in if placed diagonally. If it were a triagle, the cover could just fall in perpendicularly. However, if it were a circle, it cannot fall in because it is the same shape all round. No matter what angle, it cannot fall in.
2006-06-15 20:27:37 · answer #4 · answered by King of Kings 2 · 0⤊ 0⤋
thats a simple question!!!
If you build the cover square, it will fall down into the man-hole once you hold it vertically, but if you build it round--it wont! Its all because of the shape!
Plus its easy to roll if the cover is round!
2006-06-15 20:28:13 · answer #5 · answered by THE BEAST 3 · 0⤊ 0⤋
Because man-holes are round, duh.
But seriously, the first answer is right... it is impossible for one of those covers to fall into the hole. Try it sometime, you'll hurt yourself before it goes in.
2006-06-15 20:27:47 · answer #6 · answered by smokingun 4 · 0⤊ 0⤋
Because man-holes are round in shape to avoid corners and bends that may retain waste material as it flows through.
2006-06-15 20:30:08 · answer #7 · answered by lalskii 3 · 0⤊ 0⤋
All good answers BUT man-holes in to roofs are rectangle so why can't street man-hole covers be rectangle as well ???
2006-06-16 01:39:48 · answer #8 · answered by Anonymous · 0⤊ 0⤋
So they can be replaced very quickly, without having to line up corners or sides; put them down any which way, and they fit!
2006-06-15 21:55:07 · answer #9 · answered by Steiconi 3 · 0⤊ 0⤋
Because the hole is round, so they had to make a round cover. ;-)
2006-06-16 03:08:19 · answer #10 · answered by phantom_phan_2005 3 · 0⤊ 0⤋