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Geezer
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Some Facts About Electron Microscopes

Tue Jan 08, 2013 1:32 am

The basic purpose of this thread is an attempt on my part to demonstrate why I feel that the metric system of measurement is far superior to the English system; I suppose a few may be wondering, why do I even care ? The answer to that is of course, a couple of reasons;

First, in my long and somewhat "lack luster" career, I have been engaged in quite a few different "activities", a few of which I thought of as merely a "hobby"; (even though I have never been particularly fond of that word); in one of these activities, you find yourself doing a lot of measuring.

I have always been very interested in geology, which of course, led to reading a lot of books on the subject. When you start reading about geology, you also start hearing a lot about rocks; the more you study rocks, the more you start learning about what rocks are made out of, and of course, many rocks are formed from crystals. Now, unless you're very careful, you will be reading about crystals, and next thing you know, you're "into" crystallography! If you so much as touch one book about crystallography, you're bound to start seeing photographs of gem stones, as almost (but not all) gem stones are "fashioned" from natural (and in some cases, man made) crystals.

A natural crystal, (say, an amethyst crystal), can be fashioned into a gem stone in one of two different ways; some are fashioned into rounded, dome-shaped stones. known as "cabochons", which comes from a French word, and I'm guessing that 90% of the people on A.net know more about French than I do, (which is "very little").

Probably even more gem stones are "faceted", which simply refers to the placement of numerous small, flat surfaces, or "facets", in a particular order, or "cut". When I started seeing pictures of faceted stones, I naturally became very curious as to how this was accomplished; so.......after a lot more reading......I found out; after I found out, naturally, I had to learn to do it; learning to facet entails a lot of different things, but one of them is measuring; you must do a LOT of measuring, and it MUST be extremely "precise" ! Now.........as far as I know, absolutely NO ONE uses the English System of measurement in faceting gem stones; why you ask ? Mainly because, it won't work ! You can do many things using inches and feet, but you won't get far in faceting gem stones with it !

Most gem stones end up in jewelry; say, you want to make a neckless, with a big amethyst as the main stone; unless you're also a goldsmith, (haven't gotten there yet), you're going to need a "mount"; guess what.....all gem stone mounts come in "mm" sizes ! As in 3 mm, 4mm, 9mm, and so on. So, right off the bat, as soon as you start faceting stones, you MUST become familiar with "millimeters", which of course, are part of the metric system ! That was just one of my activities that led me to learn about the metric system.

Another "activity" was astronomy; I got interested in astronomy, then had to learn about telescopes, (which have to do with optics), which led to microscopes, (which are needed to look at gem stones )............anyway, I became very interested in microscopes, and even became curous about electron microscopes. You can imagine my joy, when I ran across this 10 or 12 year old copy of Nat Geo, that had this fabulous article about electron microscopes ! It contained information that was SO useful, So important, some of which I hadn't heard about before, that I spent damn near a week making this chart, a 3ft X 4ft copy of which will hang on my library wall, (just as soon as I can get around to making it.)

I think anyone studying this chart for more than 6 seconds will realize that A. it would be impossible to do all of this with feet and inches, and B. people would laugh at you if you even tried to !

It all starts with the centimeter; ( hell, just study the damned chart ! )

Charley


Some Facts About Electron Microscopes
Stupidity: Doing the same thing over and over again and expecting a different result; Albert Einstein
 
vikkyvik
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RE: Some Facts About Electron Microscopes

Tue Jan 08, 2013 2:08 am

Huh?

Just because metric is used in one or two industries doesn't mean it's better. There are plenty of industries that use English units, but again, that doesn't support it being better.

Quoting Geezer (Thread starter):
I think anyone studying this chart for more than 6 seconds will realize that A. it would be impossible to do all of this with feet and inches, and B. people would laugh at you if you even tried to !

Um. Ever heard of a thousandth of an inch (a mil)? A millionth of an inch (a microinch)? Quite possible, and certainly used.

Quoting Geezer (Thread starter):
It all starts with the centimeter; ( hell, just study the damned chart ! )

To be technical, it all starts with the meter, since a centimeter is one hundredth (centi-) of a meter.

All that said, metric is WAY better. But not for the reasons you've listed. The very basic reasons for me are:

1.) It's all base-10.
2.) All the units are easily interrelated. Example:

1 Liter = 1 decimeter = 1 kg of water
1 Watt = 1 Joule / 1 second = 1 Volt * 1 Amp
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AR385
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RE: Some Facts About Electron Microscopes

Tue Jan 08, 2013 2:39 am

Very interesting Charley. I also have a love for telescopes. Me and my father used to stargaze with the variety of telescopes he gave me through the years.

Now, tell me, what are you doing with your time these days?
   
 
cmf
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RE: Some Facts About Electron Microscopes

Tue Jan 08, 2013 3:10 am

Quoting vikkyvik (Reply 1):
All that said, metric is WAY better. But not for the reasons you've listed. The very basic reasons for me are:

1.) It's all base-10.
2.) All the units are easily interrelated. Example:

This really is what it comes down to. The inconsistency in converting between in, ft, yd, mi is amazing. Then try to connect with other measurements and it just gets worse. In metric we only have this situation with time.
Don’t repeat earlier generations mistakes. Learn history for a better future.
 
mirrodie
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RE: Some Facts About Electron Microscopes

Tue Jan 08, 2013 3:21 am

Metric is just so easy. Works well in all math.

Thousands of an inch.....what a joke. Seriously.
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StarAC17
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RE: Some Facts About Electron Microscopes

Tue Jan 08, 2013 3:44 am

Quoting vikkyvik (Reply 1):
Just because metric is used in one or two industries doesn't mean it's better. There are plenty of industries that use English units, but again, that doesn't support it being better.

If you are in a job where you have to a lot of converting like geology or engineering it makes you much more productive and much less likely to make a mistake. I get that some units are so common place that its hard to get rid of them like height, weight etc.

One thing that has always bugged me is that we equate pounds and kilograms which are not physically the same thing a kilogram is a unit of mass and pound is a unit of weight (a force) your mass applies when influenced by gravity.

A pound and a newton are describing the same thing (weight) which is dependent on the force of gravity so if you weighed yourself on the moon it would be 1/6 your earth weight but your mass is the same.

A kilogram and a slug (which really isn't used anymore) are units of mass.
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vikkyvik
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RE: Some Facts About Electron Microscopes

Tue Jan 08, 2013 4:24 am

Quoting StarAC17 (Reply 5):
If you are in a job where you have to a lot of converting like geology or engineering it makes you much more productive and much less likely to make a mistake.

I'm in engineering. I use English units all day every day. Not by choice, but it is what it is, and it's really no more difficult than using metric for my job.

I agree that converting from English to metric and back certainly can introduce errors. But if you're wholly in one or the other, I doubt it leads to more mistakes.

Quoting StarAC17 (Reply 5):
One thing that has always bugged me is that we equate pounds and kilograms which are not physically the same thing a kilogram is a unit of mass and pound is a unit of weight (a force) your mass applies when influenced by gravity.

Unless you're talking about a pound-mass.   But yes, it's dumb.

Quoting StarAC17 (Reply 5):
A kilogram and a slug (which really isn't used anymore) are units of mass.

Don't have a need slugs in my job, but used them all the time for English unit aerospace calculations in school.
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Molykote
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RE: Some Facts About Electron Microscopes

Tue Jan 08, 2013 5:19 am

Quoting Geezer (Thread starter):
I spent damn near a week making this chart, a 3ft X 4ft copy of which will hang on my library wall

I can't be the only one to have chuckled about that in a post fellating the metric system.

In all seriousness, there is no disputing that the metric system is superior by any objective standard. However, being employed in the aero industry, I end up working with both systems often enough that neither bother me.

I spent a summer in Europe in the 1990's and the comparison of measurement systems was a frequent enough point of "small talk". Although I agree that the metric system is superior, I wish that I had a Kroner for every time a European told me that the metric system was "more intuitive" before referring to a distance of "one half centimeter" or "one third of a kilometer"!  
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rwessel
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RE: Some Facts About Electron Microscopes

Tue Jan 08, 2013 5:22 am

Quoting StarAC17 (Reply 5):
One thing that has always bugged me is that we equate pounds and kilograms which are not physically the same thing a kilogram is a unit of mass and pound is a unit of weight (a force) your mass applies when influenced by gravity.

A pound and a newton are describing the same thing (weight) which is dependent on the force of gravity so if you weighed yourself on the moon it would be 1/6 your earth weight but your mass is the same.

A kilogram and a slug (which really isn't used anymore) are units of mass.

Of course people screw up units all the time, although the standard system makes it easier. One of my favorite examples is the utter inanity of ISP (the basic measure of efficiency of a rocket engine) being in *seconds*, just because someone way back when though be could cancel pound-force units in the numerator of a fraction with pound-mass units in the denominator.

The same *could* happen in SI - in SI people occasionally use the kgf (kilogram force, or the force a kilogram exerts downward at the surface of the earth, or 9.8N) as a convenience. You could easily imagine someone making that same mistake with kg(mass) and kgf, except that the "popular" unit (the kg) is actually the correct one in SI (measuring mass), where as the pound is a measure of force*, but which has been misused as a measure of mass incessantly for centuries, whereas the Newton is widely understood to be the correct unit of force.

Then the standard system has all sorts of odd customary units (quick, how many gallons in an acre-foot?), which is seriously frowned upon in SI. SI also eases that by having a much better defined system of base units, and what the standard units derived from that are - so it all actually hangs together pretty well, even the "official" non-SI units (liter, hectare, tonne....).


*except, of course, when it's troy or avoirdupois – quick: how much more thrust do I need if I load 100 ounces of gold on my rocket?
 
Geezer
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RE: Some Facts About Electron Microscopes

Tue Jan 08, 2013 7:25 am

Quoting vikkyvik (Reply 1):
To be technical, it all starts with the meter, since a centimeter is one hundredth (centi-) of a meter.

You're right of course; and I know that......the reason I said it all starts with the centimeter, is because I was thinking of my chart when I wrote that;

All that said, metric is WAY better. But not for the reasons you've listed. The very basic reasons for me are:

1.) It's all base-10.

Which is exactly what I was talking about with my chart ! I think many may be missing part of my point here;
From the 12 years I went to school, I doubt very much if there was ever 3 words mentioned about the metric system; I graduated from high school; at my graduation ceremony, my machine shop teacher remarked......"the only thing you were good at was cafeteria and toilet" ! The former because I liked to eat, the latter because we occasionally sneaked a smoke in the men's rest room. I went into the Navy and spent 4 years working on submarines. My service school taught me to weld and fabricate heavy metal; then, 41 years driving trucks; yet along the way, I have learned quite a lot about many things, all on my own; from faceting gem stones, building all manner of things out of metal and wood, raised 5 children, all of which are college educated, and my oldest son has a PhD in EE; I have also read more books than most people I know, and I remember much of what I read; (I can even recite Archimedes Principle from 8th grade science class). I noticed a bit of "wisdom" in an old Nat Geo magazine, realized it's important, and sure......I took some time to design that chart; My question then is this.........why do you feel the need to criticize me, before agreeing with me ? I have never claimed to be anything "special", but I do have a few things "going for me"; uncommonly good health for one, a fantastic new wife that I found at age 70 and married at age 80; I feel I could have done much better had I gone to college, but I didn't go to college, so I had to make my living working with my hands, and with my back; I only hope you will have done as well when you reach my age.

Quoting AR385 (Reply 2):
Now, tell me, what are you doing with your time these days?

Ha ! Wasting much of it on forums it would seem; I don't have that much free time, actually; what with 2 cats that need to be fed 4 times a day, plus 3 dogs that must be fed once each day, and as my wife does "at home" dialysis, it keeps me hopping, moving the cartons of supplies from the front porch to the bed room, then keeping all of the "drain" bags emptied and taken out to the trash; when we go out of town for a few days, it's either haul 3 or 4 cartons of solution sets with us, or call Fresenius and co-ordinate a delivery of supplies to where we are at. It requires a lot of planning and logistics. In between all of that, I'm usually attempting to keep up, with my reading; (haven't had much time for TV recently)

Charley
Stupidity: Doing the same thing over and over again and expecting a different result; Albert Einstein
 
vikkyvik
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RE: Some Facts About Electron Microscopes

Tue Jan 08, 2013 7:44 am

Quoting Geezer (Reply 9):
why do you feel the need to criticize me, before agreeing with me ?

Because it's not a criticism. I don't understand some of your points, and others I don't agree with.

I agree with you that metric is better. But not for the reasons you listed in your opening post, as I said.
I'm watching Jeopardy. The category is worst Madonna songs. "This one from 1987 is terrible".
 
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flyingturtle
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RE: Some Facts About Electron Microscopes

Tue Jan 08, 2013 3:24 pm

Another cool stuff is the DIN page format:



A4 has the double size as the A5 page, which is in turn double the size of an A6 page, and A0 is 1.189 meters x 0.841 meters large, which (nearly) equals one square meter.

"By 1975 so many countries were using the German system that it was established as an ISO standard, as well as the official United Nations document format. By 1977 A4 was the standard letter format in 88 of 148 countries. Today the standard has been adopted by all countries in the world except the United States and Canada. In Mexico, Costa Rica, Colombia, Venezuela, Chile and the Philippines the US letter format is still in common use, despite their official adoption of the ISO standard."

http://en.wikipedia.org/wiki/Paper_size#A_series

David
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cptkrell
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RE: Some Facts About Electron Microscopes

Wed Jan 09, 2013 12:49 am

I dunno; it's still easier for me to think of 8.5 X 11 (in) rather than 215.9 X 279.4 mm. for a sheet of letter paper. Plus the measurement has only one half the digits. But that's just me. regards...jack
all best; jack
 
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flyingturtle
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RE: Some Facts About Electron Microscopes

Wed Jan 09, 2013 9:46 am

Quoting cptkrell (Reply 12):
I dunno; it's still easier for me to think of 8.5 X 11 (in) rather than 215.9 X 279.4 mm. for a sheet of letter paper. Plus the measurement has only one half the digits. But that's just me. regards...jack

No, because you never have to measure that paper at all. "I want a pack of US letter paper", the same we say here with "I want a pack of A4 paper". You aren't in the paper industry, are you?   


David
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cmf
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RE: Some Facts About Electron Microscopes

Wed Jan 09, 2013 10:53 am

Quoting cptkrell (Reply 12):

I dunno; it's still easier for me to think of 8.5 X 11 (in) rather than 215.9 X 279.4 mm. for a sheet of letter paper. Plus the measurement has only one half the digits. But that's just me. regards...jack

Change your thinking to A4. It is a quarter of the characters needed to write the measurement and a sixth of the characters needed to write letter paper.

Even better, lets you enjoy the advantages almost everyone else in the world found worthwhile to make the change. I do not understand why this country is incapable of changing to better solutions. It can't be impossible when the government managed to change the size they use, of course they changed to an old system.
Don’t repeat earlier generations mistakes. Learn history for a better future.
 
cptkrell
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RE: Some Facts About Electron Microscopes

Wed Jan 09, 2013 4:19 pm

It's still easier for me to think of just a piece of letter paper than try to remember "A4". Hell, when I think of A4, I picture a McDonald Douglas Skyhawk, not a Xerox copier.   regards...JACK
all best; jack
 
Geezer
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RE: Some Facts About Electron Microscopes

Thu Jan 10, 2013 3:28 am

Quoting flyingturtle (Reply 11):
Another cool stuff is the DIN page format:

David; You have just proven that "you are never too old to learn new things" ! I never even HEARD of the "din format" before;

is it based on the metric system or what ? I'm glad I started this thread now........I'm finally learning something new.


Back in the 70's or 80's, (not really sure just when). there was a big "push" to get the U.S. to adopt the metric system; to "soften the blow", they decided to use both systems "side by side" for a time, then let the old system just die of old age. For a few years, cars had MPH on the outer dial of the speedometers. and KPH on the inner dial; I'm not sure of this, but I think this is when carmakers also started using a few metric fasteners also; along the way, everyone had to start getting metric hand tools, and it was intended for SAE tools to eventually be phased out; come to think of it........I never have learned exactly what came of the effort to "change over", but the whole thing finally petered out, the "KPH" dials quit being put on the speedo's; come to think of it.......many states even started putting up signage on Federal and Interstate Highways with both miles and kilometers on them. I guess it all just came down to "old habits die hard". I don't even hear anyone talking about a metric "change-over" any more, but we still have to have two sets of hand tools to work on cars; I had to replace the water pump on my Kubota tractor a few weeks ago,(which is all metric), and I could see it was going to be a bitch, due to the tight clearances, so I went to Harbor Freight and bought a bunch of new tools; (all metric); it made a really "tough" job into a breeze!


Some one explain this to me.........I think I'm getting two different things mixed up here; my wife has chronic kidney disease and does "at home" kidney dialysis now; four times each each day she has to drain the solution from the last "fill" (4 hours before), then "fill" from a plastic IV bag that contains 2000 ml of dextrose solution; afters the solution has been in for 4 hrs, she drains it back out; now.....usually, more comes out than went in; after she's finished "refilling", we have to hang the drain bag on a little spring scale hanging from the IV stand, and weigh it carefully; the spring scale is marked in grams on one side, and "newtons" on the other side. then, the exact weight is recorded in a notebook, usually, when she's finished draining, the bag will weigh any where from 2,000 grams, to as much as 3,200 grams; so.....I think I have been getting "volume" mixed up with "weight"; I guess my question is, how do grams compare to ml (milliliters) ? (I'm getting mixed up just trying to type this!) Also........I'm guessing that the "fill" bags contain somewhat more that a quart; how does one "convert" "or compare) 2,000 ml (volume) to one quart (volume) ? I just checked....a fill bag with 2,000 ml (volume) weighs from 2,100 to 2,200 grams; (I think that was what was getting me confused)

Charley
Stupidity: Doing the same thing over and over again and expecting a different result; Albert Einstein
 
rwessel
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RE: Some Facts About Electron Microscopes

Thu Jan 10, 2013 9:02 am

Quoting Geezer (Reply 16):
but we still have to have two sets of hand tools to work on cars

Not really, there are basically no non-metric parts left on any (new) cars, except the wheels and speedometers.

Quoting Geezer (Reply 16):
the spring scale is marked in grams on one side,

Which is actually a lie, spring scales measure force (aka weight), grams are a unit of mass.

Quoting Geezer (Reply 16):
"newtons" on the other side.

And Newtons are a proper measure of force, and technically should be the only thing on a spring scale. We commonly conflate the two because there's a fairly fixed relationship between weight and mass here on earth (9.8N is what 1kg weighs on the surface of the Earth).

Misuse of units is common, of course. Much cooking (especially baking) in Europe is done with recipes where ingredients are specified by mass (eg. "100g sugar"). And then cooks have *volume* measuring devices calibrated for different common substances:

http://www.amazon.de/dp/B004P8J3BA

With calibrations for flour, sugar, rice, salt and butter, as well as showing (metric) cups (250ml).

Quoting Geezer (Reply 16):
how do grams compare to ml (milliliters) ?

1ml of pure water at 3C is 1g. At different temparatures that will vary, and if the water isn't pure that will impact things as well (for example, disolving a bunch of salt in some water will significantly increase its density).
 
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Kiwirob
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RE: Some Facts About Electron Microscopes

Thu Jan 10, 2013 9:59 am

Quoting Geezer (Reply 9):
a fantastic new wife that I found at age 70 and married at age 80

Congrats Charlie, I thought you were still a few years away from getting hitched again.

Quoting flyingturtle (Reply 11):
Today the standard has been adopted by all countries in the world except the United States and Canada.

Although the legal profession in many countries still like using legal sized paper.
 
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flyingturtle
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RE: Some Facts About Electron Microscopes

Thu Jan 10, 2013 10:09 am

Quoting Geezer (Reply 16):
I guess my question is, how do grams compare to ml (milliliters) ? (I'm getting mixed up just trying to type this!) Also........I'm guessing that the "fill" bags contain somewhat more that a quart; how does one "convert" "or compare) 2,000 ml (volume) to one quart (volume) ? I just checked....a fill bag with 2,000 ml (volume) weighs from 2,100 to 2,200 grams; (I think that was what was getting me confused)

How much does the empty bag weigh?

Blood has a density of 1060 g / liter, blood plasma one of 1030 g / liter... this is extremely close to water, which has 1000 g / liter.

And:

1 Quart = 0,946352946 Liter = 946.3 ml

1000 ml = 1 Liter = 1,05668821 Quarts

Quoting Geezer (Reply 16):
I never even HEARD of the "din format" before;

is it based on the metric system or what ? I'm glad I started this thread now........I'm finally learning something new.

The DIN paper size is insofar metric as the A0 sheet is one square meter big, and A1 is half as big (folded in the middle), the A3 is again half as big... the side lengths follow the proportion 1 to the square root of 2.

And another trick is this one: You know the density of paper, e.g. 80 grams per square meter. Because you know that A0 has double the size as A1, and A1 double the size as A2 etc. you instantly know how much a single sheet of A4 paper weighs - 40 grams for A1, 20 grams for A2, 10 grams for A3, and presto, 5 grams for A4.

Really helps with sending international letters, where 20 grams (envelope, pages and stamps) often are the limit for the cheapest tariff.


David
Reading accident reports is what calms me down
 
Geezer
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RE: Some Facts About Electron Microscopes

Fri Jan 11, 2013 12:44 am

Quoting flyingturtle (Reply 19):
And another trick is this one: You know the density of paper, e.g. 80 grams per square meter. Because you know that A0 has double the size as A1, and A1 double the size as A2 etc. you instantly know how much a single sheet of A4 paper weighs - 40 grams for A1, 20 grams for A2, 10 grams for A3, and presto, 5 grams for A4.

I don't see how you know how much a square meter of paper weighs, unless you know the thickness of the paper ? And there must be as many different kinds of paper as there kinds of insects ! I don't know that they would vary that much, but again, I'm sure different kinds of paper surely must vary in weight some ?


[quote=flyingturtle,reply=19]1 Quart = 0,946352946 Liter = 946.3 ml

This is what I have been wondering about! I already knew that a liter was more than a quart, but I thought there was probably a bigger difference than this. So essentially, when the wife first does a "drain and fill" exchange, she's walking around with slightly more than a gallon of dextrose solution in her abdominal cavity, (2,000 ml), and by the end of the four hour "dwell" time, this has become about six pints! (3,000 ml) (No wonder she tires easily when she does very much walking.)

Charley
Stupidity: Doing the same thing over and over again and expecting a different result; Albert Einstein
 
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flyingturtle
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RE: Some Facts About Electron Microscopes

Fri Jan 11, 2013 1:04 am

Quoting Geezer (Reply 20):
I don't see how you know how much a square meter of paper weighs, unless you know the thickness of the paper ? And there must be as many different kinds of paper as there kinds of insects ! I don't know that they would vary that much, but again, I'm sure different kinds of paper surely must vary in weight some ?

Well, you see the density on the package when you buy it.  

80 grams / square meter is normal office paper.

120 g/m^2 and more are used for drawings, and for paintings you can use even heavier paper (it doesn't soak up the water that well). There is air mail stationery that only weighs 50 g/m^2.


By the way, do you know the exact name of the dialysis your wife has to do? I've only heard of the normal dialysis which is done at the hospital.



Kind regards, David
Reading accident reports is what calms me down
 
rwessel
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RE: Some Facts About Electron Microscopes

Fri Jan 11, 2013 8:17 am

Quoting flyingturtle (Reply 21):
Well, you see the density on the package when you buy it.

80 grams / square meter is normal office paper.

120 g/m^2 and more are used for drawings, and for paintings you can use even heavier paper (it doesn't soak up the water that well). There is air mail stationery that only weighs 50 g/m^2.

More-or less the same system with US-style papers. It's consistent for most writing/bond/copier/printer type papers, and the "weight" of a paper is expressed as the number of pounds a 17x22 ream of 500 sheets weighs (and there we go misusing units again, but that's another rant). Other than being a somewhat arbitrary size, it's simple enough (equivalent to four sheets for letter-size stock).

The mess is that other types of paper have their own standard. Newsprint, for example, is measured on the basis of 24x36 500 sheet ream weighs, so 20lb newsprint is considerably thinner than 20lb bond. But while the basis for bond makes some sense (exactly four sheets), 24x36 doesn't really match anything - most broadsheets are closer to 22x30.

Paper heading for offset printing follows yet another standard.

This is an excellent illustration of why SI is good for you: every application doesn't have its own set of measures. It's not just about the base units.
 
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ManuCH
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RE: Some Facts About Electron Microscopes

Fri Jan 11, 2013 4:25 pm

Quoting rwessel (Reply 8):
The same *could* happen in SI - in SI people occasionally use the kgf (kilogram force, or the force a kilogram exerts downward at the surface of the earth, or 9.8N) as a convenience. You could easily imagine someone making that same mistake with kg(mass) and kgf, except that the "popular" unit (the kg) is actually the correct one in SI (measuring mass), where as the pound is a measure of force*, but which has been misused as a measure of mass incessantly for centuries, whereas the Newton is widely understood to be the correct unit of force.

Wait, now I'm confused. I've grown up in an all-metric country, and done all my schools in metric. I know very well the difference between kg and N.

Everything I know about English units is from hearsay and from the Internet. I always assumed that when people in the US refer to the "pound" (and write "lb") they refer to a mass. When looking this up on Wikipedia (yeah I know, but better than nothing), I find the following:

http://en.wikipedia.org/wiki/Pound_(mass)
http://en.wikipedia.org/wiki/Pound_(force)

So there are 2 different pounds, one for mass, and one for force, which happen to be "almost the same" on Earth surface. Also, they both share the abbreviation "lb" (among others).

Quote:

In the gravitational systems, the weight of the mass unit (pound-mass) on Earth's surface is approximately equal to the force unit (pound-force). This is convenient because one pound mass exerts one pound force due to gravity

So why is it that you infer that people refer to the (incorrect) Pound-force, as opposed to the Pound-mass, when they say "I weigh 170 pounds"? Who decided which one is default?  
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flyingturtle
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RE: Some Facts About Electron Microscopes

Fri Jan 11, 2013 4:32 pm

Quoting ManuCH (Reply 23):

...when my father studied physics, he still had to know the erg, the dyn and other stuff...  


David
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vikkyvik
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RE: Some Facts About Electron Microscopes

Fri Jan 11, 2013 7:56 pm

Quoting ManuCH (Reply 23):
So why is it that you infer that people refer to the (incorrect) Pound-force, as opposed to the Pound-mass, when they say "I weigh 170 pounds"?

Because they say "weigh". Weight is a force.  

How is pound-force incorrect there? Maybe it's not what people mean, but it is what they say!

Quoting flyingturtle (Reply 24):
the erg, the dyn

I've had both of those crop up in crossword puzzles recently....
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ManuCH
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RE: Some Facts About Electron Microscopes

Fri Jan 11, 2013 11:15 pm

Quoting vikkyvik (Reply 25):
Because they say "weigh". Weight is a force.  

How is pound-force incorrect there? Maybe it's not what people mean, but it is what they say!

Well, over here people say "I weigh 80 kg" because it's less awkward than saying "my mass is 80 kg", but it's just a word issue. What they are inherently talking about is mass, not the force.

By analogy, I thought that in colloquial language, when you talk about weight in the US, you refer to the pound-mass.
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rwessel
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RE: Some Facts About Electron Microscopes

Fri Jan 11, 2013 11:22 pm

Quoting ManuCH (Reply 23):
Everything I know about English units is from hearsay and from the Internet. I always assumed that when people in the US refer to the "pound" (and write "lb") they refer to a mass. When looking this up on Wikipedia (yeah I know, but better than nothing), I find the following:

http://en.wikipedia.org/wiki/Pound_(mass)
http://en.wikipedia.org/wiki/Pound_(force)

So there are 2 different pounds, one for mass, and one for force, which happen to be "almost the same" on Earth surface. Also, they both share the abbreviation "lb" (among others).

Quote:

In the gravitational systems, the weight of the mass unit (pound-mass) on Earth's surface is approximately equal to the force unit (pound-force). This is convenient because one pound mass exerts one pound force due to gravity


So why is it that you infer that people refer to the (incorrect) Pound-force, as opposed to the Pound-mass, when they say "I weigh 170 pounds"? Who decided which one is default?

lb-m is a "proper" unit of mass only in the same sense that kg-f is a proper unit of force. And you'd generally avoid kg-f in polite company. Part of the confusion is that the meaning of an unadorned "pound" is ambiguous given the long usage as a measure of mass. You'd simply never take kg as a measure of force, or need to write it a kg-m. Of if anyone ever started using "Newton-mass" to refer to
 
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ManuCH
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RE: Some Facts About Electron Microscopes

Fri Jan 11, 2013 11:28 pm

Quoting rwessel (Reply 27):
lb-m is a "proper" unit of mass only in the same sense that kg-f is a proper unit of force. And you'd generally avoid kg-f in polite company. Part of the confusion is that the meaning of an unadorned "pound" is ambiguous given the long usage as a measure of mass. You'd simply never take kg as a measure of force, or need to write it a kg-m. Of if anyone ever started using "Newton-mass" to refer to

OK got it, this makes sense. Thank you for the explanation.
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RE: Some Facts About Electron Microscopes

Wed Jan 16, 2013 9:45 am

I can't believe I started all of this! I'm learning something new every minute !

Now..............I knew most of this stuff before I ran across that 12 yr old Nat. Geo magazine where I read the article which cause me to make my chart, which in turn is what caused me to to offer my opinion about the superiority of the metric system; however, what I DIDN"T know, and what really blew my mind at the time, was the last step on the chart, the Fermi.

That's actually what caused me to make the chart; at the time, I was unaware that this unit existed; I mean, to discover that something could be 10 trillion times smaller than a centimeter really boggled my mind; yet everyone seems more interested in different kinds of paper!

Maybe I better start a thread about paper ? Much of what I know about paper I learned on the first job I had when I got off of active duty from the Navy in 1955; I got a job as a detail draftsman at a company called Black-Clawson, which made what's known as "stock preparation equipment" for the "wet end" of the paper manufacturing business. Plus, the town I lived in had about five different paper mills, Sorg Paper Co, , Crystal Tissue, Gardner-Richardson Paper, and two more that I don't remember the name of. About half the people in my home town worked in a paper mill, and everyone else worked at Armco Steel.

Anyway, I'm really glad to see so many people share my opinion about the metric system making so much more sense than the English System. It's not everyday that I come up with anything that so many people agree with!

But back to my main point........has anyone ever had any "experience" with the Fermi ? I remember when Dr. Enrico Fermi built the world's first atomic pile under the bleachers at the University of Chicago and created the first nuclear chain reaction, which I suppose is why they started calling the thing a "reactor". At the time, it was pretty "scary", as no one knew anything about nuclear physics; (or I should say, no one outside of the physicists); when I first read that article, I was very happy that they had honored Dr. Fermi by naming that unit after him; I've read a few books about all of the world's great physicists, and Enrico Fermi was certainly among the greatest; (IMHO anyway)

BTW.........Working in a drafting room was educational, and I learned a lot, but it was't my cup of tea; I ran into a guy I had gone to high school with, and he had a steel truck, and I took a ride to New Jersey and back with him, next thing I knew, I was driving one ! ( If I had it all to do over again, I think I would have become a traffic cop; ( there would be a LOT of people either learning to drive right, or they'd be walking !)

Charley
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sebolino
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RE: Some Facts About Electron Microscopes

Wed Jan 16, 2013 1:40 pm

It's very odd to write sizes in fraction of centimeters ...

An Angstroem is 0.00000001 cm ?? Wow, actually everybody uses the notation 10^(-10) m for an Angstroem, 10^(-15) m for a fermi ...

And yes, the metric system is far superior when you do science and technics. In everyday life I don't know, but I don't see the point of working with 2 different systems ...
 
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casinterest
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RE: Some Facts About Electron Microscopes

Wed Jan 16, 2013 7:26 pm

Quoting Geezer (Reply 29):
I mean, to discover that something could be 10 trillion times smaller than a centimeter really boggled my mind

Charley,
They are all points of measurement.

Technically you could have something 10 to the Infinite power smaller than a cm or m, as long as it is a specific length. Measuring it would be an issue probably, but still theoretically possible

You will like the atto, zepto, and yocto from the below chart of metric prefixes. they are 1 thousandth, 1 millionth, and 1 billionth of a femto respectively.

http://www.chemteam.info/Metric/Metric-Prefixes.html
Twenty years from now you will be more disappointed by the things you didn't do than by the ones you did..So throw off the bowlines. Sail away from the safe harbor. Catch the trade winds in your sails. Explore. Dream. Discover.--Mark Twain
 
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flyingturtle
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RE: Some Facts About Electron Microscopes

Wed Jan 16, 2013 9:39 pm

To measure such extremely small things, you can use a Raster Tunnel Microscope.


IBM, written in Xenon atoms



David
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Geezer
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RE: Some Facts About Electron Microscopes

Thu Jan 17, 2013 6:35 am

Quoting casinterest (Reply 31):
You will like the atto, zepto, and yocto from the below chart of metric prefixes. they are 1 thousandth, 1 millionth, and 1 billionth of a femto respectively.

I looking at that chart..........I see that multiplying by ten. you arrive at the angstrom after 8 steps; and the "yocto" is at the tenth step; did they run out of names or what ? The "Fermi" is at step no. 13

One thing is for certain...........while I do enjoy gradients, I would never in a 1000 years make a mathematician or a physicist !

And the guy at IBM that lined all of those atoms up into "IBM" had a hell of a lot better eyesight than I do........Pretty remarkable!
Stupidity: Doing the same thing over and over again and expecting a different result; Albert Einstein
 
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flyingturtle
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RE: Some Facts About Electron Microscopes

Thu Jan 17, 2013 11:06 am

Quoting Geezer (Reply 33):
And the guy at IBM that lined all of those atoms up into "IBM" had a hell of a lot better eyesight than I do........Pretty remarkable!

Well, they actually used the tiny tiny tiny little needle of that Raster Tunnel Microscope to put the Xe atoms there... http://en.wikipedia.org/wiki/Scanning_tunneling_microscope

http://en.wikipedia.org/wiki/Atomic_force_microscope (which is a lot cooler)


David
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casinterest
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RE: Some Facts About Electron Microscopes

Thu Jan 17, 2013 1:12 pm

Quoting Geezer (Reply 33):
I looking at that chart..........I see that multiplying by ten. you arrive at the angstrom after 8 steps; and the "yocto" is at the tenth step; did they run out of names or what ? The "Fermi" is at step no. 13

Charley, each step in that chart is a factor of 1000(1 time 10 to the 3rd power) . The Fermi as you call it, is a femtometer. or 1 times 10 to the -13 centimeters. However that is 1 times 10 to the -15 meters. The atto zepto and yocto are all smaller than the fermi.
Twenty years from now you will be more disappointed by the things you didn't do than by the ones you did..So throw off the bowlines. Sail away from the safe harbor. Catch the trade winds in your sails. Explore. Dream. Discover.--Mark Twain
 
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flyingturtle
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RE: Some Facts About Electron Microscopes

Thu Jan 17, 2013 3:03 pm

Quoting casinterest (Reply 35):

Yeah, I learned the most-used prefixes by heart when I was 7. Million, Milliarde, Billion, Billiarde, Trillion, Trilliarde, Quadrillion, Quadrilliarde (German, all in long scale), and milli, micro, nano, pico...



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rwessel
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RE: Some Facts About Electron Microscopes

Fri Jan 18, 2013 9:09 am

Quoting Geezer (Reply 29):
back to my main point........has anyone ever had any "experience" with the Fermi

While not Fermi's (as in a femtometer/fm), but femto as a SI prefix gets some mileage*. Femtofarads (fF) is a common unit for measuring capacitance in individual circuits on modern semiconductor chips. Although that’s partly the result of a Farad being somewhat absurdly large a unit.

*pun fully intended

Quoting sebolino (Reply 30):
An Angstroem is 0.00000001 cm ?? Wow, actually everybody uses the notation 10^(-10) m for an Angstroem, 10^(-15) m for a fermi ...

FWIW, Angstrom not SI, and its use is formally discouraged, and while is still usage, it's definitely declining (nm seems ro be the most common alternative).

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