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I found your site while looking for something else, and, well, that's an hour of my life I'll never get back... and I'm glad of it :) Great stuff! I'll be back!
Gorge Branchaud <gwillybjatcapital.net>
Clemons, NY USA - Friday, December 05, 2003 at 18:31:24 (PST)

Great internet site, the "Germ Theory of Education" applies to history texts extensively, hence historians are grouped together with used car salesmen and politicians, including those who use original sources. The 2nd largest problem with the truth in historical textbooks are the influences from the entertainment media. At least with science you can make corrections, with history this bcomes increasingly difficult with time. ie.; Ronald Ragan
Kurt Lewis <Kurtlewis51atmsncom>
Conowingo, MD USA - Thursday, December 04, 2003 at 21:18:40 (PST)
Reply to poster asking "If you skydive through a cloud, do you get wet?" - You certainly do! It's one of those things one is supposed to avoid when skydiving, because of the potential hazards of bad visibility. But when it happens, one gets an appreciation for how much water a cloud contains, or more precisely, how much water is contained in the volume of cloud through which one passes.

(I'm new to this site, don't know whether 2 topics in one post are allowed but here goes)

Re: billb's proposed open acquarium + soap bubble experiment to demonstrate that CO2 doesn't expand rapidly to fill the room - I wish I'd thought of that when a pulmonary specialist (of all people) tried to tell my wife and me that CO2 is "lighter than air"! I've even read that claim in an elementary-level science book. I find this alarming! If a lie is propagated widely enough, it's accepted as common knowledge". I believe an excellent counter-offensive to bad school science is promoting science experiments at home. This would be greatly facilitated by the publication of good books for young experimenters such as were available in my younger days (50's-60's). We even had a newspaper columnist who published home experiments in the local paper. Perhaps you know of some currently available resources that you would recommend to your readers.

(While I'm at it, might as well try 3 topics)

Reply to poster asking "If electrons travel slowly, why does the light come on quickly?" (I hope I've quoted accurately, couldn't find the post when I looked back) -

The water analogy, despite its faults, illustrates very well many properties of electrical circuits. If a long hose iscompletely filled with water (as a conductor is filled with free electrons) and connected to a faucet, one need only crack the faucet open a small amount to observe a prompt response at the end of the hose. The water can be moving quite slowly, but the motion is telgraphed quickly. - Dick N.
Dick N.
Manchester, NH USA - Monday, December 01, 2003 at 18:16:53 (PST)

I remember an experiment I did in Gr. 9 that supposedly demonstrated some different forms of energy and how they can accelerate a chemical reaction. In this case, it was some salt dissolving in water.

To demonstrate heat, we heated the water, and predictably, the salt dissolved faster.

However, to demonstrate mechanical energy, we were instructed to stir the salt in the water. In retrospect, I don't believe this really demonstrates mechanical energy. All that is happening is that you are creating greater frequency of contact between water molecules and the salt. If you didn't stir, then you'd only have a puddle of highly concentrated salt water sitting at the bottom, which has a lower propensity to dissolve salt than a low concentration of salt in water.

Thanks for the site! All throughout elementary school and high school, I was one of those kids that science teachers either loved or hated, asking the tough questions that put the teachers on the spot.
Timothy Chu <chut7athotmailcom>
Vancouver, BC canada - Thursday, October 09, 2003 at 12:20:58 (PDT)

Blue Sky

If air did indeed have a blue tint to it, then why at night do stars, planets, and the moon not look blue? Or even in the daytime, wouldn't the sun itself look blue? Well, we all know they don't; and they would have to be if air was inherently blue. I'm still thinking that Rayleigh scattering is why the sky is mostly blue...
Dustin <zeoliteatdespammedcom>
TX USA - Wednesday, October 01, 2003 at 16:53:07 (PDT)

nice site you have! bookmarked it and hope you keep it up! cu
Elke <infoatneue-witzige-sms-sprueche.de>
germany - Tuesday, September 23, 2003 at 01:54:15 (PDT)
Dear Sir,

Your article on traffic jams is very interesting to my mind. It closely parallels many thoughts I've had on the subject previously. Here in France road signs indicating "lane closed at 600m" seem like an invitation to French people to stay in lane until the very last possible tyre squealing second. Usually, I try to be the peace maker by creating space...which usually garners me no grace with the fastards behind me.

Being a recently qualified pilot I found your article on airfoils to be confusing, possibly due to the humour/ sarcasm which I didn't follow entirely. Obviously, that is not intended as a crticism of your fine site. Having been "taught" both theories by different lecturers and having had difficulty with both of them as theories I was much hoping that your clear presentations would help me. Sadly not. I'm ignorant and confused as ever.

Regards, Kevin.

I'll continue to read some other aspects of your site.
Kevin Dowdall <k_dowdallathotmailcom>
Orleans, France - Saturday, September 20, 2003 at 20:06:39 (PDT)

There are two (among several) profound science myths taught as fact that have always bugged me because they are the foundations on which science supposedly builds. If the foundation is defective, it makes it impossible to build a coherent, useable science. One myth concerns aerodynamic lift, which you have correctly covered on your site. A succinct explanation is that a wing is a reaction engine. A pound of air deflected at a given velocity will result in a pound of force at a given acceleration applied to the wing in a direction dependent on the angle of incidence (or angle of attack). The angle of deflection is equal to the angle of incidence, same as with light rays, and the direction of lift is the resultant of the two angles. Secondly, the dynamic theory of pressure in a gas (fast moving molecules) is in direct conflict with the dynamic theory of heat (fast moving molecules). The dynamic theory of heat (though not correct) reasonably explains why heat causes matter to melt, expand, vaporize, if cold (absence of heat) causes molecules to coelecse, shrink and solidify. If the theory of heat is true, that heat causes energetic molecules to fly apart, then the dynamic theory of pressure in a gas which calls for energetic molecules bouncing off the walls of a container, is wrong. If both theories are true, then a pressurized tank of air would be constantly giving off heat, and would be a limitless source of energy--a perpetual motion machine on the molecular level. The actual simple fact is that pressure in a gas and expansion in solids is a "field effect". When energy, in any form, is added to the atoms of matter, the atomic radius expands. When matter iscompressed, the matter pushes back with a force equal to the change in energy density of the substance. The energy density of a substance can be changed by changes in temperature and/or specific volume. A substance is "neutral" only when its energy balance is in equilibrium with its local environment. If it is not in equilibrium, energy will flow until equilibrium is attained. This is the law of entropy, and the law of conservation of energy, combined.
Lee Fellows <frgatiocom>
Austin, TX USA - Saturday, September 20, 2003 at 10:20:12 (PDT)
In your article on why clouds stay aloft, I think you should avoid the use of "light/lighter", "heavy/heavier" when you mean "less/more dense". Your usage will only confuse people who do not understand the difference between weight and density.
alec <a_von_daleatyahoo.co.uk>
chesterfield, UK - Thursday, September 11, 2003 at 12:29:02 (PDT)
ceiling robot. Like a hovercraft but in reverse.
http://www.geocities.com/davidvwilliamson/hover.html about half way down

david williamson <davidvwilliamsonathotmailcom>
london, uk - Tuesday, September 09, 2003 at 08:13:15 (PDT)
people who don't know but don't know that they don't know do my head in very badly.
david williamson <davidvwilliamsonathotmailcom>
london, uk - Tuesday, September 09, 2003 at 08:07:36 (PDT)
There have been couple of evenings I have been outside and happened to look up at the wires and noticed them bouncing. Was just curious as to what causes that?! They don't always bounce. Just every now and then (wind isn't even blowing!). Actually, I guess it's pretty much the biggest wire. That's what I've noticed. Myself and some of friends that have noticed that would greatly appreciate and explanation. Thank you.
becky <rrstjohnatchartermi.net>
lake linden, mi USA - Wednesday, July 23, 2003 at 12:06:30 (PDT)
I thought I'd like tocomment on how Wings work. I don't offer any theory, but if you fly slowly (30 mph) with large wings (as in an ultralight), you feel as if you are floating. In other words, it feels as if you are riding on top of something. It is like being in a canoe on water, but more smooth. When you float on water, there is not less water pressure above, just air. In other words, the air is not really a factor contributing to floating on water. It is water displacement. It seems like wings work something like that (I say that because that is what it feels like). If there was NO air on top of the wing and lots underneath, the plane would still float on the air (FLYING!!). Not very scientific, I apologize for that.
IL USA - Tuesday, July 22, 2003 at 16:34:53 (PDT)
Concerning airfoils, wing cross sections and such. Once, to annoy the traditionalists, I explained lift using centrifugal force, the air flowing across the top of the wing creates a partial vacuum because it traverses a curve. Well, I knew it was wrong at the time, but it was funny.
icecycle (john f stepp)
USA - Tuesday, July 22, 2003 at 09:02:17 (PDT)
I'd like to throw my article in on the lift-creation explaination and see if it generates any thoughts, or suggestiions...

Brian Adkins <brianmadkinsatearthlink.net>
NC USA - Friday, July 18, 2003 at 06:52:13 (PDT)
ThANK YOU, THANK YOU, THANK YOU!!! Finally someone who has actually held a bar magnet up to acompass and seen that the north end of the compass needle points to the south end of the bar magnet and consequently to the South Pole of the Earth..or as I like to call it, the Santa Claus pole, making the penguin pole the Noth Pole. I have heard and explanation that the actual name of the Santa Claus Pole is the "North Attracting Pole" whose name has been shortened....erroneously...to the "North Pole"....but what ever, bravo!!

A new misconception.... that you can balance an egg on end if you hold it still long and patiently enough for the yolk to sink to the bottom, thereby lowering the center of mass making the egg more stable. Actually, it is the albumin that sinks, being more dense than the lipid yolk. Prove this by setting an egg in a narrow beaker of vinegar and wait for the shell to react with the vinegar. You can then see inside the egg and see that the yolk is floating at the top.

Another, more immediate way to observe this is to separate several eggs. Add the whites from about three or four eggs to a graduated cylinder. Add only one of the yolks. The yolk floats on the top of the whites......... Doing is believing .......

So thanks for dispelling myths and for making the seemingly obvious even more obvious.....
Joanne Suttile <jsuttileatsmesorg>
San Juan Capistrano, CA USA - Sunday, July 13, 2003 at 22:33:02 (PDT)

"look misty blue, and a thousand miles of air look opaque"

I think it should say, "...look(s) misty blue..." and "...miles of air look(s)..." Fine site
philip <philip_edlesatyahoocom>
nyc, ny USA - Wednesday, July 02, 2003 at 19:25:10 (PDT)

Hi Bill,

I’m great fan of yours, and I love your site, it is just so inspiring.

I want to say something about the “gravity in space is zero?” part. You state that gravity is the force that pulls objects towards the Earth, but this is also a misconception. It is known in general relativity (at least to people that actually scrutinize general relativity) that gravitation is caused by space-time curvature that causes “mass”; bodies are closed together by the enclosing force of space-time reaching equilibrium of potentials. So gravity is rather a pushing force, not a pulling force.

p.s – Just to drive the point home, know that matter-energy is a concentrated form of space and time.
Jerry Amos <spawnicatumpirecom>
Earth, somewhere in the outskirts of the Milky Way - Wednesday, June 18, 2003 at 11:47:25 (PDT)

In your section on clouds you say "But we also know that hot air rises". It doesn't. Less dense air rises. This misconception that hot air rises causes umpteen questions about why the troposphere is warmer at the bottom than the top if "hot air rises".
Steve Symonds <cam.steveatbigpondcom>
Tabulam, NSW Australia - Friday, June 06, 2003 at 20:44:01 (PDT)

While your article is correct in that light from the sun is not parallel, there is the unfortunate problem of light-scattering caused by the earth's atmosphere. Your examples prove only that there is atmospheric scattering, and not that sunlight is truly parallel in nature.
[Huh? My example is about the sun's surface, not about atmospheric scattering. Because each tiny point on the surface of the sun emits light in ALL DIRECTIONS, light from the sun as a whole is not parallel. The light doesn't act as if itcomes from a tiny point at the center of the sun. That's why the diagram says "wrong." If the earth had no atmosphere, my explanation would remain the same. -billb]

A different way of putting it is that the sun is a sphere, and light leaving that sphere goes straight. If all light from this sphere went directly away from the center of this sphere, then the only light the earth would get would be from an area on the sun smaller than the diameter of the earth itself! This would make for a tiny sun in the sky indeed it would like the earth seen eight light-minutes away. The apparent size of the sun matched with the amout of sunlight we can detect would therefore lead us to believe that the lightcoming from the sun goes in many directions, not just straight form the center and out (or perpendicular to the tangent of the apparnet surface of the solar body, if you want to get painfully technical).

I have only just started exploring this site, and I like what I see so far. I gather there's a lot of electrical stuff in herer, from the posts I've seen. That is good, since I am in the business of teaching electronics, I'm always game for improving my delivery.
Daniel Paradis <daniel.paradisatnavy.mil>
Lemoore, CA USA - Monday, June 02, 2003 at 16:22:22 (PDT)

I am looking for two references on errors in textbooks. Cannot find either . One is Weaver 1965 and the other is Lehrman 1973. Does anyone know these?? Please help. On the light side. One of my preservice teacher students said that a little boy in her class told her "when something is scientifically impossible, it cannot be done by magic" ...sad but true!
Linda Schaffer <lcschafatyahoocom>
Albuquerque, NM USA - Friday, May 30, 2003 at 21:59:47 (PDT)
Very interestingcomments on the airfoil theory controversy. I have always wondered: If the traditional flat on the bottom, curved on the top causes lift theory is totally valid, then how does a plane fly upside down? The fact that they do would indicate that angle of attack is a significant factor, among others.
Doug Moore <Trogloditeataolcom>
Vernon Hills, IL USA - Friday, May 16, 2003 at 11:40:47 (PDT)
well your wrong there is gravity in space there hase to be if there wasn't all planets whould be falling and traveling to one spot in space you nob you have no idea what you are going on about.Um... are you reading the same article as me? I say that there *IS* gravity in space! Go read it again.
justin <silver_sharkl2attelstracom>
townsville, Qld AUS - Tuesday, May 13, 2003 at 18:02:18 (PDT)
Could You please answer this question if u know it....If i went skydiving and went through a cloud would i get wet? stupid i know but it will clear a long lasting debate. thank-you
Marilyn <s3531564atvu.edu.au>
Melbourne, VIC Australia - Friday, May 09, 2003 at 04:54:19 (PDT)
Based on http://amasci.com/miscon/miscon4.html#mist, what is the difference between "water vapor," a transparent gas, and steam, which is also a transparent gas?
Jeff Seigle <jeff.seigleatcox.net>
Vienna, VA USA - Thursday, May 08, 2003 at 07:47:36 (PDT)
Good Site! It's too bad that nearly everyone who has posted here is stupid and that is why they cannot appreciate your site. Thanks for the laugh everyone!
Chris <na>
Canada - Wednesday, May 07, 2003 at 22:23:27 (PDT)
You write:

"This is very different than the oft-quoted rule that "gases always expand to fill their containers." This rule only works correctly if the container is totally empty: the container must "contain" a good vacuum beforehand. However, we all live in a gas-filled environment. All our containers are pre-filled with air."

The other gasses don't really affect the expansion of the new gas; under normal conditions the mean distance between collisions is so large that the gasses (and even different molecules of the same gas) move roughly independently.
[Wrong. The simplest tabletop experiments with gases in the open air show that they don't expand. I suggest that you try some. Fill a bowl with bromine gas (it's bright orange) and watch what happens. It sits there without expanding. Yes, it does eventually diffuse outwards to fill the room, but this takes many, many hours. And if you trust theory more than experiment, please GO AND LOOK UP the mean free path for gas molecules at STP. Is it large? No, in fact it's around 10^-4 millimeter. Your description of gas behavior is only true when mean free path is extremely large, i.e. for extremely low pressures (such as those inside a neon sign's tube, or the conditions high in the Earth's ionosphere.) But down here at the Earth's surface the mean free path is very short, a gas diffuses very slowly, and a gas has significant viscosity (i.e. it behaves more like a liquid than like a hailstorm of atoms.) And as I said, it DOES NOT expand to fill its container. -billb ] Essentially, each molecule takes something between a random walk and a free ballistic "bouncy ball" path; they don't "croud each outher out" or even impose much viscosity. It takes time for the a gas to fill the space, but unless there is heat exchange or some other similar interaction, the process proceeds about the same if the first gas is there or not. [No. You're describing the conditions at millitorr pressure, not at 760 Torr. Try this: fill an open-topped aquarium with carbon dioxide gas. Make some soap bubbles with a bubble-wand and allow the bubbles to drop into the aparently empty aquarium. They hover! They lie upon the invisible "surface" of the dense pool of gas. If the gas expanded immediately to fill the room, then this demonstration would be impossible. -billb]

USA - Friday, May 02, 2003 at 08:28:57 (PDT)

I find your site very well thought out and informative. Your examples are excellent and show why "dumbing down" something always has negative repercussions.

I would like tocomment on the problem you discussed with the "filled balloon/empty balloon" experiment. While it is indeed correct that the simplified explanation that is presented does not seem to prove that air has weight, your analysis of the problem is, like the experiment itself, not sufficiently involved. In truth the fact that a filled balloon weighs more than an empty one does prove that air has weight. You point out correctly that the balloon actually contains compressed air". However, this is the very condition which proves air has weight. If air did not have weight, putting more of it into the container viacompression would not increase the weight of the container and its contents. The analogy with living in a sea of air is also innappropriate because water, unlike air, is icompressible. Lifeforms totally surrounded by water could not perform the experiment because water cannot becompressed so that more could be forced into the container.

[ No, that's a very distorted version; it's not what appears in the texbooks. You have to go read some children's actual textbooks, then you'll see the problem. Read this part carefully:

Many books contain a incorrect experiment which purports to directly demonstrate that air has weight. A crude beam-balance is constructed using a meter stick. Deflated rubber balloons are attached to the ends, and the balance is adjusted. One balloon is then inflated, and that end of the balance-beam is supposed to sag downwards. A large amount of air supposedly weighs more than a small amount of air.
If the textbooks contained the demonstration which you describe below... then I wouldn't becomplaining. A comparison of compressed and ucompressed air would be worthwhile. But that's not what the textbooks do. Instead they tell the child (or the teacher) tocompare a full balloon with an empty balloon, and they never mentioncompression, nor do they mention the carbon dioxide from your breath, nor the water droplets from condensation. They say that a filled balloon weighs more than an empty one, and the ballooncomparing demonstration is supposed to prove this.

The incorrect experiment is the one above. It's all about filled and empty containers, not aboutcompressed and uncompressed air, but unfortunately they use balloons as the containers. If they used filled and empty garbage bags, then they'd prove that filled and empty containers weigh the same (and they do weigh the same as long as the container is immersed in air, and the pressure inside and outside is the same.] See balloon misconception


Balloon A contains X amount of air at ambient air pressure.

Balloon B contains 5X amount of air at 5 times ambient air pressure.

Hypothesis: Weight of X amount of air = 0.00 lbs. Assume Balloons A & B are identical and weigh 1.00 lbs. (They're huge!)

Thus, weight of Balloon A will be the same as Balloon B, if and only if our Hypothesis that air has no weight is true. When the scale is checked it will bcome apparent however that Balloon A and Balloon B do not weigh the same. This expressly disproves our hypothesis thereby rendering the hypothesis that air has weight to be true.
Dean Kimes <kitasiatattbicom>
Aurora, CO USA - Wednesday, April 30, 2003 at 09:28:21 (PDT)

In regards to the North Pole of the Earth actually being the "South" Pole of the Earth...

The whole problem with this conundrum is that the "N" on acompass stands for "North-seeking end" not "North magnetic pole". Unfortunatly, "seeking" will not fit on acompass needle... hence to confusion over opposites attracting. Thecompass needle is facing it's "south pole magnetic end" toward toward the "North pole end" of the Earth's magnetic field... Rather than the Earth's field actually being switched - the compass needle has been mislabled for the sake of brevity.

[ Sorry, you're wrong. This is not open to debate; it's a very old physics standard similar to the standard for polarity of electric charge. We define "positive charge" as the charge on the proton. We define "north-type pole" as the pole of a rod-magnet which seeks the northern part of the Earth. The definition of "north-type pole" does not refer to the Earth, it refers to the poles of electromagnets. The definitions are part of contemporary physics and are even part of Maxwell's Equations. I assume that you've heard of the "right hand rule" taught in introductory electromagnetism courses. And because we've defined "north-type pole" in this way, we're forced to say that the northern part of the Earth contains a south-type pole. That way it can attract the n-type end of all thecompass needles.

Perhaps it would be better if things were backwards: if electrons were defined as positive charge, and if north-seeking magnet poles were defined as south-type poles. Unfortunately the physics standards both for "positive" and for "north" were adopted over a century ago and it's far too late to try to make them less confusing.

If you see a textbook which says differently, that textbook is wrong. There are lots of K-6 textbooks which get this wrong. I've yet to find any physics textbook at the undergrad level or above which make this fundamental error. - billb]

Julie Knapp <littleredhenschoolatyahoocom>
River Falls, WI USA - Tuesday, April 29, 2003 at 07:52:34 (PDT)

I didn't know there were 4 or 5 explanations regarding the theory of airfoils. I would have thought this subject was wrapped up long ago. But I'm not surprised.

What about the Kasper wing? It has some curious properties.
Chuck jeronimo <chasjeronatyahoocom>
San Jose, CA USA - Tuesday, April 01, 2003 at 22:00:14 (PST)

I'm trying to teach a grade 6 class about airfoils. Although it would be easy for me to go with the standard Bernoulli theory...which is what I seem to keep finding, I'm wondering if there is an easy way to explain this concept so student actually understand...rather than simply having to accept the the air speeds up over the curve (creating lower pressure). I was also wondering if it's possible to use water to help them understand this concept any better???

I've read a lot on your sight..and although it addresses these issues, I just need it simplified, so students can understand...and so I can answer they're questions with answers rather that..."it's that way just because it is". Thanks!

[ The correct version of the "Bernoulli" explantion turns out to be identical to the "Newton" explanation. In other words, there's a pressure difference across a wing because the wing is deflecting air. And also, the wing deflects air because there is a pressure difference. This is one of those situations where two effects are connected together. They both happen at once, and one does not cause the other. They are both caused by air hitting a wing which has a tilted trailing edge. The tilt of the whole wing doesn't matter, only the angle of the wing's trailing edge is significant. Below is one way to understand it.

In order to generate a lifting force, the trailing edge of an airfoil must be sharp. Whenever air passes over any airfoil, the trailing edge of the airfoil determines the angle of air flow. The leading edge does not. This happens because air has inertia, and when the air flows away from the tilted trailing edge, the air keeps going in the same direction as the angle of the trailing edge. But the air ahead of the leading can approach the wing from most any direction. The leading edge doesn't control the approach of the icoming air. However, the air near the leading edge is greatly affected by the trailing edge, since the air is flowing off the trailing edge at a downwards angle. This down-flowing air stream gets in the way of any air which tries to flow horizontally under the wing. The air under the wing must slow down. Also, because the air flows off the trailing edge at a downwards angle, an empty pocket should form directly above the down-flowing air. However, a pocket does not form. Instead, the air approaching the front of the wing is pulled up and over the wing and it speeds up just enough to keep that pocket filled. The air above the wing flows very fast just as the air below the wing flows slowly.
Finally, here are two important facts regarding airfoils:
  1. If the trailing edge of the airfoil does not deflect the air downwards, then the airfoil does not create a lifting force.
  2. The air above the wing flows much faster than the air below the wing. The air above the wing greatly outraces the air below, and the separated upper and lower parcels of air never meet up again.
I got this explanation from reading papers on fluid mechanics. It's based on the 2-D potential or "Cirulation" analysis, which in turn is based on the electromagnetic analogy to fluid flow. Above is the simplified version. For those with interest in the role of the trailing edge in generating lift, search the web using keywords "circulation" and "Kutta condition." -billb]

V. K <vlkleinhathotmailcom>
Thunder Bay, ON Canada - Saturday, March 29, 2003 at 17:17:08 (PST)

well then explain a fully symectrical airfoil which uses speed alone wright? wrong it uses air passing by at different rates caused be gravity <--- dont orget about her laws . so yes thou you present a intresting quagmire you are wright in some ways wrong in others
filicia22x <filicia22xatpeoplpepccom>
cocoa beach, fl USA - Monday, March 17, 2003 at 19:14:13 (PST)
I love this site but dont have time to browse right now. So I am going to ask a simple question. In my children's elementary school they are taught that n/0=0. In school, and even recently in college calculus, I have been taught that n/0 is undefined. The school says that I am "nitpicking" by protesting this, but it bothers me. Am I wrong? The math series they teach btw is Saxon.

[People who are threatened by those who point out mistakes can ALWAYS cry "nitpicker." But remember, you can't turn a valid complaint into "nitpicking" just by labeling it that way. Also, if someone starts ignoring errors and declaring them to be "nitpicking", it's very bad. It destroys the system of checks and balances and opens the door to any amount of errors at all. Click on all those links to articles about the shameful state of K-6 textbooks. The books got that way because the publishers are in the habit of saving face and making excuses rather than simply rolling up their sleeves and fixing the mistakes. Unfortunately, before they can fix anything they have to take responsibility and own up to having a problem in the first place. It's embarassing to admit to mistakes, but it's much worse to start covering them up in order to avoid public embarassment.

In truth, n/(small number) equals a large number, and n/0 is not a number, it's infinity. Your school made a genuine mistake. That'scommon and normal. Dismissingcomplaints is not normal, it's reason to fear that they've started playing "coverup" and stopped correcting mistakes, and if they did it with you, perhaps they've been ignoring lots of other complaints in the past. -billb]

Bobbi Kedzierski <bobbikedzieatyahoocom>
covington, ga USA - Sunday, March 16, 2003 at 22:40:08 (PST)

Re which is the right explanation about wings and lift:

1) an old engineer once told me that either explanation is OK, imagine what would happen if they gave different answers and an actual aircraft used bernulli on the port wing and newton on the starbord.

2) isn't angle of attack a functional derived variable? That is 0 AOA is where the wing generates no lift. For any symmetric airfoil it's easy to find geometericly, for anything else it's easiest to determine experimentally.

[ Bernoulli's equation works fine. We can explain 100% of the lifting force using Bernoulli, or we can explain 100% by using Newton's laws (after all, the Bernoulli equation is BASED on Newton's laws.) It's not Bernoulli that's wrong. The problem is with the "wing shape explanation" of lift; the one which claims that the parcels of air must race to the trailing edge in order to join together. It's also called the "popular explanation" or the "longer path explanation." It is wrong, since the parcels of air which are divided at the leading edge of an airfoil DO NOT rejoin at the trailing edge. They remain separate. Path lengths along the wing surfaces are not important in generating lift. In fact the upper parcel outraces the lower one and they never rejoin at all. The explanation is also wrong because a wing does not have to be curved on top and flat on the bottom (in fact, a symmetrical wing with equal path lengths flys just fine, it just stalls more easily than a cambered wing.) -billb]
A J Brislen <abrislenatdeltanetcom>
Laguna Niguel, ca USA - Monday, March 10, 2003 at 10:36:37 (PST)

I think a lot of this is minor things about this, i know a lot of people can get screwed up by this, hey i hear people ask how to spell the simplest words in the english language. But i hate hearing people start with the whole capital letter thing...especially people who type things like: 'Its THIS way not THAT way' its makes it sound like bullshit and somone who is overly critical. Just sayin what i think.
octwo <not tellin>
Novato, CA USA - Wednesday, February 26, 2003 at 09:18:43 (PST)
About airfoils. Were you aware that iceboats, which use sails (which are airfoils, too), can sail faster into the wind than the wind itself. If you try to explain lift solely on the basis of reactive forces, how would this be possible? In fact if you maximize the "push" or reactive force of the wind by sailing downwind with sails perpendicular, you would find yourself travelling significantly slower than when sailing upwind.
Joe Ward <brodnackatyahoocom>
Oakland, Ca USA - Thursday, February 20, 2003 at 14:07:28 (PST)
I would like to thank you for such an awesome site. This information helped me on my science fair project. I got 1st place! I would like to know a little bit more about citrus fruits generating electricity. Do you have any information? Thank you and keep up the great work!
rich, wa USA - Tuesday, February 18, 2003 at 18:53:28 (PST)
i got ur site from googlecom first of all im willing to thank u people for giving such valuable information. ur article "how cell phone works" helped me a lot i gave seminar on this topic along with slide show in my class room and i got appricaited by our head and principal thanq once again and keep youncouraging youngsters thnq
nanda kishore mallela <nandakishore_eceatrediffmailcom>
tirupati, USA - Thursday, February 13, 2003 at 05:55:54 (PST)
Wow give me information abaut misconception in chemical equilibrium, this very important for my thesis post graduate.
Unggul Sudarmo <smunsaatindo.net.id>
Solo, Java Indonesia - Wednesday, February 12, 2003 at 21:26:38 (PST)
Juniorszone-providers of online primary school education offering literacy,numeracy keystage2 strategy based on national curriculum,uk
Rajinder Gill <juniorszoneatyahoo.co.uk>
Ludhiana, Punjab India - Wednesday, February 12, 2003 at 04:54:17 (PST)
What is your opinion on the Testatika free-energy machine? Does it capture the imbalances in the air, much like harnessing lightening?
Gorge West <georgewestathotmailcom>
Los Angeles, CA USA - Wednesday, February 12, 2003 at 00:06:36 (PST)
its a good thing that i found this site because i'm in high school(and am taking the usual science courses)
leonard, tx USA - Thursday, January 23, 2003 at 17:55:43 (PST)
Excellent list of misconceptions! I'm training to be a science teacher and I have to do a report on a misconception in science. I was stuck on what to do, but now i'm stuck for what not to do!!
T Smardon <edmtrsatbath.ac.uk>
Bath, UK - Friday, January 10, 2003 at 08:47:27 (PST)
i dont think you are a nitpicker, but even if you are, that is good, because it is always good to be more exact. i would like to know if you think that static electricity is harmfull from powerlines, because i am doing an investigation on harmfull effects from powerlines and one researcher, peter staheli, says that the real danger from powerlines is not electromagnetic radiation, but static electricity. Thanks. also, would it be too much to ask for you to e mail me with an answer instead of just posting it on your website? if it is, its ok, ill check it on your website. nicolas
nicolas luna <nicolaslunaathotmailcom>
puebla, mexico - Thursday, January 09, 2003 at 12:43:40 (PST)
this program didn`t really have what i needed but it did have every thing i didn`t need but thats wuz o.k. i`ll just nchange my project thanks
melissa <Q T Pie504atcenturytelcom>
hineston, la USA - Monday, January 06, 2003 at 14:11:33 (PST)

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