rookie1ja Posted March 31, 2007 Report Share Posted March 31, 2007 Round vs. Square - Back to the River Crossing Puzzles Why is it better for manhole covers to be round rather than square? This old topic is locked since it was answered many times. You can check solution in the Spoiler below. Pls visit New Puzzles section to see always fresh brain teasers. Round vs. Square - solution You can turn a square manhole cover sideways and drop it down the diagonal of the manhole. You cannot drop a round manhole cover down the manhole. Therefore, round manhole covers are safer and more practical than square ones. Link to comment Share on other sites More sharing options...
Guest Posted June 5, 2007 Report Share Posted June 5, 2007 another interview question =) Link to comment Share on other sites More sharing options...
Guest Posted June 12, 2007 Report Share Posted June 12, 2007 The obvious answer is that manhole covers should be round because manholes are round. But your answer is more informative. Link to comment Share on other sites More sharing options...
Guest Posted June 13, 2007 Report Share Posted June 13, 2007 Correct-a-mundo!!! There is not a single shape (besides perfectly round) that could not be positioned in a way that would cause it to fall in the hole. None what-so-ever! It's funny to think that even Manhole Covers were thought out well before mass production began. You would just think they were round because they were going on a ROUND HOLE...lol Also, seeing as how the damn things weigh about 38 gazillion pounds, trying to lift one is not an easy task. The method to move them typically is "Rolling them". Needless to say, trying to ROLL a 4 edged square hunk of metal would Link to comment Share on other sites More sharing options...
Guest Posted June 21, 2007 Report Share Posted June 21, 2007 Correct-a-mundo!!! There is not a single shape (besides perfectly round) that could not be positioned in a way that would cause it to fall in the hole. None what-so-ever! It's funny to think that even Manhole Covers were thought out well before mass production began. You would just think they were round because they were going on a ROUND HOLE...lol Also, seeing as how the damn things weigh about 38 gazillion pounds, trying to lift one is not an easy task. The method to move them typically is "Rolling them". Needless to say, trying to ROLL a 4 edged square hunk of metal would <!-- s:oops: --><!-- s:oops: --> Veracity, the veracity of your statement is suspect: "There is not a single shape (besides perfectly round) that could not be positioned in a way that would cause it to fall in the hole." , You couldn't be more wrong! heard of "constant diameter curves" ? A circle is just one of many such curves: read This and This That said, you are bang on target with your second statement about the ease of rolling R Link to comment Share on other sites More sharing options...
Guest Posted June 21, 2007 Report Share Posted June 21, 2007 Correct-a-mundo!!! There is not a single shape (besides perfectly round) that could not be positioned in a way that would cause it to fall in the hole. None what-so-ever! It's funny to think that even Manhole Covers were thought out well before mass production began. You would just think they were round because they were going on a ROUND HOLE...lol Also, seeing as how the damn things weigh about 38 gazillion pounds, trying to lift one is not an easy task. The method to move them typically is "Rolling them". Needless to say, trying to ROLL a 4 edged square hunk of metal would Veracity, the veracity of your statement is suspect: "There is not a single shape (besides perfectly round) that could not be positioned in a way that would cause it to fall in the hole." , You couldn't be more wrong! heard of "constant diameter curves" ? A circle is just one of many such curves: read This and This That said, you are bang on target with your second statement about the ease of rolling R Well, Look at that.. Your right. I stand corrected. I love learning new things. Thank you for taking the time to add a link to back your reasoning up....!! Link to comment Share on other sites More sharing options...
Guest Posted June 21, 2007 Report Share Posted June 21, 2007 While it may not be correct that it is the only shape that won't fall through the hole, it appears to be the only one that won't fall through and actually serves the purpose of a manhole cover -- to cover the manhole. Of course, if you were just trying to prove someone wrong so you looked smart, congrats! Dave Link to comment Share on other sites More sharing options...
Guest Posted June 21, 2007 Report Share Posted June 21, 2007 While it may not be correct that it is the only shape that won't fall through the hole, it appears to be the only one that won't fall through and actually serves the purpose of a manhole cover -- to cover the manhole. Of course, if you were just trying to prove someone wrong so you looked smart, congrats! Dave LOL I wasn't going to say anything figuring if I had it would look like I was Making Excuses to Justify my being Incorrect... But since you mentioned it...lol Link to comment Share on other sites More sharing options...
Guest Posted July 7, 2007 Report Share Posted July 7, 2007 One of the English' coins is a condiam (constant diameter curve). Link to comment Share on other sites More sharing options...
Guest Posted July 11, 2007 Report Share Posted July 11, 2007 a round lid covers more area of the square then a square lid to help from it leaking (why they dont want it to leak its a sur) and you can roll it out of the way making it easier. Link to comment Share on other sites More sharing options...
Guest Posted July 24, 2007 Report Share Posted July 24, 2007 (After Google-Imaging) They condiam coins are the 20p and 50p ones. Link to comment Share on other sites More sharing options...
Guest Posted August 15, 2007 Report Share Posted August 15, 2007 a triangle shaped cover wouldnt fall into a triangle shapped hole either Link to comment Share on other sites More sharing options...
Guest Posted August 15, 2007 Report Share Posted August 15, 2007 a triangle shaped cover wouldnt fall into a triangle shapped hole either i was about to say this however i should add that it's only an equilateral triangle that won't fall through. Link to comment Share on other sites More sharing options...
Guest Posted August 15, 2007 Report Share Posted August 15, 2007 a triangle shaped cover wouldnt fall into a triangle shapped hole either i was about to say this however i should add that it's only an equilateral triangle that won't fall through. While you could create a cover/hole combination where a triangle wouldn't fall through, it is not a certainty. It all depends on the lip width and thickness of the cover material. An equilateral triangle has a maximum diameter (the length of a side) that is ~1.15 times the minimum diameter (center of a side to the opposite vertex). ______ | / | / x / |_ /___________ |--1.15x--| - Dimensions So as long as the lip isn't too wide and the cover isn't too thick, it will fall through. Turn the cover so a one side of the triangle is vertical and the bottom or top is flat against a side of the hole. /| / | / | | | | ~~~~~~~~~~~~ (long side of hole) - Side view / <- hole / / / ========== <- cover (===) ~~~~~~~~~~~~~~~~ -Top view In any non-equilateral triangle the ratio of maximum diameter to minimum diameter gets larger and it is easer to fit the cover through the hole. (sorry for the ugly drawings) Link to comment Share on other sites More sharing options...
Guest Posted August 15, 2007 Report Share Posted August 15, 2007 Well, I'd imagine because you can't fit a square into a circle. And if they didn't have a manhole itself as a circle, and had it as a square, maybe it wouldn't be right because people who climb down there are generally fat? No idea on that one there. Link to comment Share on other sites More sharing options...
Guest Posted September 15, 2007 Report Share Posted September 15, 2007 ahhh this is the stupidest question ever! Link to comment Share on other sites More sharing options...
Guest Posted September 19, 2007 Report Share Posted September 19, 2007 Its round either because people are round, and its easier to traverse, or that pointy manhole covers would bend/break. -=society works cause we think it does=- Link to comment Share on other sites More sharing options...
Guest Posted October 17, 2007 Report Share Posted October 17, 2007 There are many answers I believe some of them are of which is they are safer with no points/verticies to poke people. Fits in any orientation, square won't if you rotate them 45 degrees. As well as the others already mentioned Link to comment Share on other sites More sharing options...
Guest Posted December 1, 2007 Report Share Posted December 1, 2007 i have the perfect answer. they arent square so you dont stub your feet on them if they stick up too much. lol!! oh and haha i though this was a messed up face not a lightbulb haha Link to comment Share on other sites More sharing options...
Guest Posted December 24, 2007 Report Share Posted December 24, 2007 square would be better in my oppion because you can put hinges on it easily. Link to comment Share on other sites More sharing options...
Guest Posted January 31, 2008 Report Share Posted January 31, 2008 But hinges would either create an uneven driving surface if it was designed to have the cover flip 180 degrees, or the cover would be stick strait up perpendicular to the road. This would be a hazard since it could slam on someones head, or could make a driving hazard. Link to comment Share on other sites More sharing options...
Guest Posted February 6, 2008 Report Share Posted February 6, 2008 Why would they want hinges on it anyway? it would be way to hard to lift. Link to comment Share on other sites More sharing options...
Guest Posted February 8, 2008 Report Share Posted February 8, 2008 But what about a semi-circle? A shape that will not fall through the shape of the hole... Link to comment Share on other sites More sharing options...
Guest Posted February 11, 2008 Report Share Posted February 11, 2008 Bingo excellent logic Moreover in a unit dimension a round has more are than a square Link to comment Share on other sites More sharing options...
Guest Posted February 11, 2008 Report Share Posted February 11, 2008 A circle or condiam (continuous diameter curve) aren't the only shapes that aren't susceptible to falling through the hole: any triangle would be safe from this too. But climbing through a triangular hole would just be silly; and moving a triangular cover would be inefficient as well. Link to comment Share on other sites More sharing options...
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