I'm not joking, this might be a silly question but it would mean a lot to know the correct or convincing reason?
2006-07-17 02:10:17 · 12 answers · asked by raVen 1 in Education & Reference ➔ Other - Education
It is the strongest (structurally) two dimesional shape. It can withstand the most weight without collapsing.
2006-07-17 02:14:06 · answer #1 · answered by Tunasandwich 4 · 0⤊ 1⤋
Why is a manhole cover round? Because a square manhole cover could fall into the hole it's supposed to cover. But a round manhole cover cannot, as long as the hole is ever so slightly smaller. What property of a circle makes this true?
Is it because the circle has constant diameter? If so, we're going to have to be able to clearly abstract the idea of diameter from the circle to other shapes. So, what does a diameter mean for other shapes? What is the diameter of a square of side 1, for instance?
For any 2D geometric shape, we can define a diameter by imagining that we try to fit the shape entirely between two straight lines. Some orientations of the shape will allow the two lines to come close, and some far. To check all the possible orientations, we could imagine driving a nail through one point of the shape, turning it around that point, and measuring the widths that the shape takes up. During this process, we may get many values; we are particularly interested in the maximum and minimum values that turn up, which we will call the maximum diameter and minimum diameter of the shape.
It should be clear that the circle has constant diameter, that is, equal maximum and minimum diameters. The square of side 1 has maximum diameter sqrt(2) and minimum diameter 1.
2006-07-17 02:17:00 · answer #2 · answered by Bolan 6 · 0⤊ 0⤋
Square manhole covers have the possibility of falling into the manhole. Round manholes make this geometrically impossible.
2006-07-17 02:14:58 · answer #3 · answered by Anonymous · 0⤊ 0⤋
a few reasons
1. So it rolls easier
2. So it doesn't fall in the manhole if it is lifted/moved. Other shapes (squares for example) could fall in the manhole if they were lifted or moved, but a circle wo't - same diameter no matter which way it is turned.
2006-07-17 02:14:28 · answer #4 · answered by merigold00 6 · 0⤊ 0⤋
Hey, I happen to know this one. They are circles so that the cover can't accidently fall into the manhole. If they were any other shape, they could get crossways and fall in.
2006-07-17 02:14:36 · answer #5 · answered by fishing66833 6 · 0⤊ 0⤋
because it is the only shape that has one width.. the diameter. so if you accidentally drop it side ways, it will not fall into the hole because the diameter is still the same. unlike in a rectangle or a square.. two side of a rectangle are shorter than the other two, it will fall easily into the hole. a square has four equal sides but the diagonal is longer the side.. ok?
2006-07-17 02:21:22 · answer #6 · answered by deadmeat 3 · 0⤊ 0⤋
Because a square or rectangle would be more likely to fall thru. I read this somewhere. A circle will stay closed the best, engineers tested it somehow.
2006-07-17 02:17:22 · answer #7 · answered by marie 7 · 0⤊ 0⤋
Because then it wouldn't be called a manhole it would be called a manrectangle
2006-07-17 02:14:51 · answer #8 · answered by Wicked Wangdoodle 2 · 0⤊ 0⤋
Manhole covers were purposely made round so that they would not fall into the hole.
2006-07-17 02:14:29 · answer #9 · answered by Joe K 6 · 0⤊ 0⤋
Rectangular manholes are called trenches. Thats why
2006-07-17 02:13:25 · answer #10 · answered by Puppy Zwolle 7 · 0⤊ 0⤋
Round if more efficient use of space, With a square the corners would be wasted. It's also easier to replace a round cover as far as orientating it.
2006-07-17 02:14:17 · answer #11 · answered by Anonymous · 0⤊ 0⤋