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>
>What I've said here, of course, doesn't mean that there weren't
>situations before the late 1600s in which the force which these
>weights exerted wasn't what people were really interested in.  I'm
>sure you can find many examples of this; somebody must have wondered
>how hard he had to pull to draw a longbow, for example.  That is one
>reason that the same words came to be used for both mass and for
>force.  Nobody had any way to measure force, but objects of the same
>mass do exert pretty much the same force anywhere on the surface of
>the earth, within the precision of most measurements then or now.
>
I'm not sure if someone did'nt have a way to measure force prior to the late 
1600's and I'm pretty sure that someone did have a way to calculate static 
force prior to the late 1600's. The designers of the Church of St. Sophia in 
Constantinople (built AD 532-537) must have had some concept of force as the 
main dome on this church weighs between 3 to 8 million lbm and excerts an 
equal horizontal and vertical reaction of 3 to 8 million lbf. I don't believe 
engineering feats of this magnatude were by trail and error.  

I am trying to obtain information regarding the misaaplication of
contaminated soils in landfills.  I am a graduate student working on a
paper that will attempt to discuss the use and misuse of landfills (both
the pros and cons). Much information I have found (so far) has been pro
landfills.  I need more information concerning the misuse,
misapplication and alternatives to landfilling contaminated soils (and
why those alternatives may be better than landfilling).  Any information
(no matter how small or trival) would be greatly appreciated.  Please
email me directly; soilpure@mn.uswest.net
Thanks for all your help.
Sincerely,
Martin V. Aschenbrener

Dear Sir,
     I would like to introduce myself.  My name is Ramon N. Pescevich
and I work for Bioanalytical Systems Inc. as a field service engineer.
We sell instruments to leading medical schools, evironmental
organizations, industry and the military.  We are scientists helping
scientists.  Please visit our website at the following URL:
http://www.bioanalytical.com.
     I would like to thank you for your time.  Hoping to hear from
you.
Ramon N. Pescevich
Field Service Engineer
Bioanalytical Systems, Inc.

Postdoc: Application of Statistical Optics to Diffractive Optics 
and Pattern Recognition at the ElectroOptics Research Institute,
University of Louisville.
Field(s): information systems, optics and optoelectronics.
Job Description: 
Applicants in the following subject areas will be considered:
() Photolithography directed at three dimensional microstructures
   for diffractive optics and microoptics.
() Computer design of diffractive optics and composite distortion
   invariant pattern recognition filters. 
() Non-destructive techniques for the profiling of three dimensional
   microstructures. 
() Tracking of three dimensional objects using various images sensing
   approaches including distortion-invariant correlation filters
   and structured light illumination. 
To apply send resume, relevant reprints and list of references
incuding phone numbers and email address.
Email: rwcohn01@ulkyvm.louisville.edu 
Phone: (502) 852-7077 Fax: (502) 852-1577
http://www.ee.louisville/~eri
Address: 
     The ElectroOptics Research Institute,
     Academic Building, Rm 442, 
     University of Louisville, 
     Louisville, Kentucky 40292 (USA)
-- 
Chuck Sites              | cbsite01@starbase.spd.louisville.edu    |
\e-  e-/
System Programmer        | (502)-852-7020   FAX: (502)-852-6807    | 
\~~~>/
Electrical Engineering   |-----------------------------------------| 
/<~~~\
University of Louisville | http://www.spd.louisville.edu/~cbsite01 |
/e-  e-\

Hi everybody!
I am currently writing a thesis on Virtual Communities.
These communities can be  MUD's, websites a la The Well or ECHO, IRC and ... 
Usenet. At least, certain newsgroups.
I agree with the opions of others, who state that these virtual communities 
are a new model of community, in some ways better then the communities in real 
life.
A part of my interest lies in the commercial potential of virtual communities. 
Companies can and do learn form these communities and start to realize that 
not flashy graphics, but the possiblity to interact with others is what 
attracts people to a website.
Intergration of the game-element, live chat or forums, no anonimity etc. All 
important ingredients of a good website, make the consumer talk and be active, 
but be modest.
I have made a questionnaire on virtual communities, put the HTML-page on two 
servers.
I hope people who read this message can find the time to surf over there and 
help me better comprehend the ins and outs of life in a virtual community.
If this subject is familiar to you and you are am member at Social Cafe, Utne 
Cafe, ECHO etc. surf over here and participate.
The two URL's:


Thanks for 'listening' and perhaps for cooperating in my thesis!
Aaron Peters

"Richard White (CS)"  writes:
> On 24 Jun 1997, Dean Pentcheff wrote:
> > So here's my challenge: name five situations that are likely to occur
> > in conventional daily life where the mass/weight distinction matters.
> > Exclude cases like accurate airplane navigation (or, for that matter,
> > nuclear warhead targeting!) where people certainly are affected, but
> > without personal involvement.  Navigation systems engineers worry
> > about it, but airplane passengers don't need to.
> 
> Sidebar:  In all the airplane navigating I've done as a pilot (some of it
> even accurately), I've not yet been concerned about the weight/mass of
> anything.  Weight and balance calculations don't have anything to do with
> navigation in the kinds of airplanes I fly, so perhaps I am ignorant of
> what navigation systems engineers worry about.  What would that be? 
I was thinking about designers of GPS systems, who certainly worry
about orbital mechanics, mass, weight, etc.; or the designers of
interial naviagation systems which (I assume out of ignorance) must
depend on very accurate force measurements of a mass, for which the
precision of the force contribution from gravity is critical.
> > So, aside from the (not insignificant) intellectual pleasure of
> > drawing the mass/weight distinction, why should non-technical people
> > care? 
> 
> I was going to say that in hockey, which I play in a local recreational
> league, the goaltender is quite concerned about the 1/2 mv^2 of that hard
> little black rubber puck on an interception trajectory with his body, but
> he probably doesn't think about it in those terms.  He just says, "Ow,
> that was a hard shot."  Either that or "nya, nya, you missed me."
> 
> Maybe a better example is a car skidding on smooth ice (in winter in
> Chicago of course).  But then again, maybe the driver isn't thinking in
> terms of his car's 1/2 mv^2 but rather how much it's going to cost him
> when all that mass comes to rest against some other mass. 
Hmmm...  But does the mass/weight distinction really matter?
Blindfold a goalie and hand him two pucks, one made of styrofoam and
one of resin, and he'll instantly claim that he'd prefer being hit by
the styrofoam one.  Yes, he's "really" using the force of weight to
assess the mass of the puck, but he'd be quite correct in asserting
that he'd rather get hit by the styrofoam puck since it weighs less.
> OK, how about this.  In skydiving (my other favorite sport), the terminal
> velocity of a jumper in freefall (the steady state velocity earthward) is
> directly related to weight, not mass.  When the aerodynamic drag (measured
> in pounds) on the body exactly equals the weight of the body (also
> measured in pounds), the acceleration is zero.  Some very light skydivers
> wear weight belts, similar to scuba divers, to equalize their fall rate
> with the other jumpers in the formation.  Heavier jumpers wear baggier
> jumpsuits that increase drag, thereby enabling them to fall slower. 
> Though perhaps not considered "conventional daily life", he would have a
> different terminal velocity on mars or venus where his weight and
> aerodynamic drag are different, but his mass is the same. 
True enough.  But no one cares whether the skydivers have been
"calibrated" based on their mass in kilograms or their weight in
Newtons on the ground.  The two will be (for all practical purposes)
perfectly correlated.  Yup, it would clearly matter on other planets,
but I think I'll agree that this isn't (yet) daily life...
> Alright, let me have one more chance.  A frisbee seems to fly better if it
> has a little more mass, assuming the extra mass is distributed nearer the
> perimeter.  Paper airplanes seem to fly farther if they have some extra
> mass such as a penny taped near the center of lift.  Do these examples
> count?  How about a hammer?  More mass drives the nail farther each swing. 
> Am I even coming close here? 
In these cases the effect is gained through an increase in
weight... again _caused_ by an increase in mass in a constant
gravitational field, but does the modelmaker care whether the object
being attached masses more or just weighs more right here and now?
> I guess I can't imagine why non-technical people should care about the
> distinction between mass and weight. 
Me neither.  Wish I could come up with some reasons, though...
> Never mind.    Good question, though. 
> Happy times upon you, Richard.
Thanks for the conversation!
-Dean
-- 
N. Dean Pentcheff      WWW: http://tbone.biol.sc.edu/~dean/
Biological Sciences, Univ. of South Carolina, Columbia SC 29208 (803-777-3936)
PGP ID=768/22A1A015 Keyprint=2D 53 87 53 72 4A F2 83  A0 BF CB C0 D1 0E 76 C0 
Get PGP keys and information with the command: "finger dean@tbone.biol.sc.edu"

Dean Pentcheff wrote:
> 
> Dean Pentcheff  writes:
> > Here's a challenge for the physically-minded...
> ...
> > So here's my challenge: name five situations that are likely to occur
> > in conventional daily life where the mass/weight distinction matters.
> > Exclude cases like accurate airplane navigation (or, for that matter,
> > nuclear warhead targeting!) where people certainly are affected, but
> > without personal involvement.  Navigation systems engineers worry
> > about it, but airplane passengers don't need to.
> >
> > So, aside from the (not insignificant) intellectual pleasure of
> > drawing the mass/weight distinction, why should non-technical people
> > care?
> 
> My labmate, Chris Finelli, came up with one that strikes me as quite
> valid:
> 
> When you stand in a swimming pool you indeed weigh less, but your mass
> remains constant.  Putting a bathroom scale on the floor of a pool and
> weighing yourself there is an effective strategy for weight loss, but
> not for mass loss...
Nice answer.  Here's one that's perhaps more likely to happen:
A man runs a company that buys and sells fruit in mass quantities.  He
buys and sells the fruit by weight.  He buys, say, x tons of oranges in
Florida and pays the orchard based on the Florida weight.  He then takes
the fruit to Denver, Colorado, which I believe is far more elevated. 
Since Denver is farther away from the center of the Earth, the
gravitational pull on objects there is less.  The man weighs his oranges
again to determine the selling price, and now there's x-1 tons of fruit
by Colorado weight.  He hasn't lost any oranges (the mass is the same),
but the weight has decreased.  That means he's losing 1 ton worth of
income!
I admit there's not likely to be that big of a change in the weight, but
imagine something like this in the future, when space travel becomes
common.  People in a colony on the moon would love to pull something
like this, because everything would cost about 1/6 of what it would on
Earth.  Better to sell things by mass, from an Earth inhabitant's point
of view.
-- 
Harold Tessmann III
Summer Intern, Chemical Engineering, Ford Motor Company
My opinions are mine and mine alone.  You can't have them.