Darren New wrote:
> Actually, I've never seen anyone get the answer write to "why are 
> manholes round."  I almost hope they ask me that at my next job 
> interview, because the interviewer probably doesn't know either. ;-)

	I like the fake Feynman answer:

START

Interviewer: Now comes the part of the interview where we ask a question 
to test your creative thinking ability. Don't think too hard about it, 
just apply everyday common sense, and describe your reasoning process.

Here's the question: Why are manhole covers round?

Feynman: They're not. Some manhole covers are square. It's true that 
there are SOME round ones, but I've seen square ones, and rectangular ones.

Interviewer: But just considering the round ones, why are they round?

Feynman: If we are just considering the round ones, then they are round 
by definition. That statement is a tautology.

Interviewer: I mean, why are there round ones at all? Is there some 
particular value to having round ones?

Feynman: Yes. Round covers are used when the hole they are covering up 
is also round. It's simplest to cover a round hole with a round cover.

Interviewer: Can you think of a property of round covers that gives them 
an advantage over square ones?

Feynman: We have to look at what is under the cover to answer that 
question. The hole below the cover is round because a cylinder is the 
strongest shape against the compression of the earth around it. Also, 
the term "manhole" implies a passage big enough for a man, and a human 
being climbing down a ladder is roughly circular in cross-section. So a 
cylindrical pipe is the natural shape for manholes. The covers are 
simply the shape needed to cover up a cylinder.

Interviewer: Do you believe there is a safety issue? I mean, couldn't 
square covers fall into the hole and hurt someone?

Feynman: Not likely. Square covers are sometimes used on prefabricated 
vaults where the access passage is also square. The cover is larger than 
the passage, and sits on a ledge that supports it along the entire 
perimeter. The covers are usually made of solid metal and are very 
heavy. Let's assume a two-foot square opening and a ledge width of 1-1/2 
inches. In order to get it to fall in, you would have to lift one side 
of the cover, then rotate it 30 degrees so that the cover would clear 
the ledge, and then tilt the cover up nearly 45 degrees from horizontal 
before the center of gravity would shift enough for it to fall in. Yes, 
it's possible, but very unlikely. The people authorized to open manhole 
covers could easily be trained to do it safely. Applying common 
engineering sense, the shape of a manhole cover is entirely determined 
by the shape of the opening it is intended to cover.

Interviewer (troubled): Excuse me a moment; I have to discuss something 
with my management team. (Leaves room.)

(Interviewer returns after 10 minutes)

Interviewer: We are going to recommend you for immediate hiring into the 
marketing department.

END

Taken from:

http://www.sellsbrothers.com/fun/msiview/#Feynman

I have to strongly agree with one point - why do people keep thinking 
they are just round? I've seen *many* square shaped ones.

-- 
Copywight 1991 Elmer Fudd.  All wights wesewved


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