When I was in the eighth grade, my science teacher asked me why manhole covers are round but never told me the answer. It has been a question that has plagued my existance since that time. Perhaps you could bring closer to this chapter in my life and give me a since of completion. Here are the answers I have reasoned out:
1) Because it is the only shape where the cover cant be turned side ways and allowed to drop through the hole. Eliminates pranksters from droping the "lid" down the hole.
2) Because it allows for even distribution of force when the cover shrinks or swells because of heat. Because the cover's coefficent of linear expantion is different from that of the concrete around it, it will push on the concrete as it heats up. If the cover were square, then it would appy the most pressure in the corners, and cause the asfault or concrete to bust up there. Because it is round it has even distribution of force and keeps the area around it from busting up.
I think it may have to do with making it harder to scrape metal from the edges. If the outside edge is smooth and circular, any cuts into it for metal are very easily seen. Of course, edge design helped with that, too.
Ha, Ha, Ha! "Why are manhole covers round?" was a job interview question asked of a few software engineers who applied for jobs at Microsoft many years ago (don't know if they still ask that one). And.... LincolnCentMan got very close to the answer. I guess he had thought about it for a while
He guessed: "1) Because it is the only shape where the cover cant be turned side ways and allowed to drop through the hole. Eliminates pranksters from droping the "lid" down the hole."
Not only does it prevent pranksters from droping the lid down the hole it prevents the lid from going down the hole by accident or for any other reason. Normally there would be a worker down the hole if the lid was off so it could be very, very bad if the lid went down the hole!
<< <i>1`. So they do not makes holes on ones pockety or purse
2... So that they can be rolled and stored efficiently. >>
Wait, I read somewhere once that coins weren't stored in rolls until what?? The 1850s or something like that?? They were round well before then so that reasoning doesn't hold up.
Mrspud, The great Yogi also said, "It ain't over until it is over." So to further the hypothesis of your link: "Some people learn by hearing, some people learn by seeing, and well unfortunately some people just have to piss on the electric fence."
we actually studied this in a college course long ago. bottom line is: round is the cheapest shape to manufacture. it's also why, for example, soda cans & oatmeal canisters are round.
Ans: Vending machines, nothing else works as well as round coins. As a nation becomes more developed and acquires more vending machines or things that require coins to buy something, the coins all become round and accomodating for vending machines. Thus round coins slide and roll down the slots in a vending machine and also make it easier to detect fake coins.
On the manhole cover thing, in addition to not falling in the hole-they are a little easier to roll than they are to carry. I wouldn't want to try to roll a square or triangular manhole cover.
On the manhole cover thing, in addition to not falling in the hole-they are a little easier to roll than they are to carry. I wouldn't want to try to roll a square or triangular manhole cover.
Rolling manhole covers down a hill is pretty spectacular too, especially the stop at the bottom!
I'm not surprised nobody has revealed on this forum the REAL answer for why coins are round. The code of silence...the fear of reprisal...the heavy boot of tyranny. Nobody here will talk.
But I'm not afraid. I will not be silenced! It's obviously a conspiracy led by one big name Third Party Grading Service. Heavy lobbying, political pressure, and back room payoffs to those sleazy government officials are to blame. Coins are round because PCGS holders are made for round objects!
Warn your friends! Tell your neighbors! The truth shall set you free!!
(Must cut this short. A black helicopter just landed on my front lawn. He has a loupe around his neck, and I don't think he's afraid to use it).
Because the Greeks did it and everyone just follow their design. It could also be that pieces of metal were use for payment in the past and someone one day decided to hammer the pieces of metal that he has and they turn into circular shape.
Coin Collector, Chicken Owner, Licensed Tax Preparer & Insurance Broker/Agent. San Diego, CA
dimples
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2) When they are struck, a round planchet allows for the most efficieant distribution of force.
David
But in all honesty, I don't know....there has been all types of shapes tried thoughout the years.
BTW.....Carl, why are manhole covers round?
Hell, I don't need to exercise.....I get enough just pushing my luck.
When I was in the eighth grade, my science teacher asked me why manhole covers are round but never told me the answer. It has been a question that has plagued my existance since that time. Perhaps you could bring closer to this chapter in my life and give me a since of completion. Here are the answers I have reasoned out:
1) Because it is the only shape where the cover cant be turned side ways and allowed to drop through the hole. Eliminates pranksters from droping the "lid" down the hole.
2) Because it allows for even distribution of force when the cover shrinks or swells because of heat. Because the cover's coefficent of linear expantion is different from that of the concrete around it, it will push on the concrete as it heats up. If the cover were square, then it would appy the most pressure in the corners, and cause the asfault or concrete to bust up there. Because it is round it has even distribution of force and keeps the area around it from busting up.
3) Because manholes are round.
David
Stuart
Collect 18th & 19th Century US Type Coins, Silver Dollars, $20 Gold Double Eagles and World Crowns & Talers with High Eye Appeal
"Luck is what happens when Preparation meets Opportunity"
<< <i>Because the corner on square coins used to tear holes in the pockets of cavemen and they were always losing them. >>
You mean, they were losing.....THEM?
2... So that they can be rolled and stored efficiently.
Camelot
W.C. Fields
Louis
My wantlist & references
He guessed: "1) Because it is the only shape where the cover cant be turned side ways and allowed to drop through the hole. Eliminates pranksters from droping the "lid" down the hole."
Not only does it prevent pranksters from droping the lid down the hole it prevents the lid from going down the hole by accident or for any other reason. Normally there would be a worker down the hole if the lid was off so it could be very, very bad if the lid went down the hole!
<< <i>1`. So they do not makes holes on ones pockety or purse
2... So that they can be rolled and stored efficiently. >>
Wait, I read somewhere once that coins weren't stored in rolls until what?? The 1850s or something like that?? They were round well before then so that reasoning doesn't hold up.
The great Yogi also said, "It ain't over until it is over." So to further the hypothesis of your link: "Some people learn by hearing, some people learn by seeing, and well unfortunately some people just have to piss on the electric fence."
Have a Great Day!
Louis
seriously!
K S
Ans: Vending machines, nothing else works as well as round coins.
As a nation becomes more developed and acquires more vending machines or things that require coins to buy something, the coins all become round and
accomodating for vending machines. Thus round coins slide and roll down the slots in a vending machine and also make it easier to detect fake coins.
PURPLE!
Rolling manhole covers down a hill is pretty spectacular too, especially the stop at the bottom!
octagonal vs round .... could it be as controversial as NT/AT ... modern/classic ... toned/untoned
NOT
Top 10 Cal Fractional Type Set
successful BST with Ankurj, BigAl, Bullsitter, CommemKing, DCW(7), Elmerfusterpuck, Joelewis, Mach1ne, Minuteman810430, Modcrewman, Nankraut, Nederveit2, Philographer(5), Realgator, Silverpop, SurfinxHI, TomB and Yorkshireman(3)
But I'm not afraid. I will not be silenced! It's obviously a conspiracy led by one big name Third Party Grading Service. Heavy lobbying, political pressure, and back room payoffs to those sleazy government officials are to blame. Coins are round because PCGS holders are made for round objects!
Warn your friends! Tell your neighbors! The truth shall set you free!!
(Must cut this short. A black helicopter just landed on my front lawn. He has a loupe around his neck, and I don't think he's afraid to use it).
San Diego, CA
K S