The dangers of sleeping through Science class.

[Janus]

Last night there was a story on the local new about gas prices. During it they mentioned that some people have taken to putting nitrogen in their tires rather than air because they thought that it would improve their gas milage.
The logic behind this? Apparently they believe... now get this... that nitrogen does not expand and contract with temperature like regular air does.

 

[FredGarvin]

Oh dear lord...I'm home schooling my kids.

 

[Rach3]

Indeed they're right! The physical properties of nitrogen gas... are very different from those of nitrogen gas.

 

[Cyrus]

Just be happy they are not trying to fill their tires with 'natural gas,' if you know what I mean.

 

[mrjeffy321]

Last night there was a story on the local new about gas prices. [...]
nitrogen does not expand and contract with temperature like regular air does.

HAHAHA,
Was this a serious news story? Or did they debunk the claim?

 

[Janus]

HAHAHA,
Was this a serious news story? Or did they debunk the claim?

The furthest they went was to ask a employee of a tire shop whether he thought it would make a difference. He said that he didn't think so.

 

[brewnog]

I thought it was to eliminate the rubber perishing (oxidising) from the inside out. Obviously not a factor with car tyres, because for almost all users, they'll wear out before they age. For heavy duty and specialist tyres though, this is an issue.

Also, compressed nitrogen is dry, - compressed air will have a wetness fraction which can freeze, and can also expands a lot more with heat. I don't really buy this second argument, especially for the low pressures and low sensitivity on pressure for road use, but I suppose it's worth a thought for high performance and critical applications.


I suspect the real reason is that people saw race/rally teams using compressed nitrogen because it's more convenient, assumed that it offered a significant technical advantage, and copied them.

 

[Chi Meson]

Oh dear lord...I'm home schooling my kids.

Keep telling myself:

"be part of the solution..."


"be part of the solution..."


"be part of the solution..."

 

[dav2008]

My 2nd grade teacher told me that to convert from Celsius to Fahrenheit you just add 32 :(

 

[chroot]

Oh, dear lord, if we start catalogging the mistakes of my primary school teachers, we'll be here all day.

- Warren

 

[Archon]

I don't remember anything from primary school. Which may or may not be a good thing...and I'm starting to think it's a good thing, actually...

 

[Astronuc]

WE have a second Science Jokes thread?

 

[brewnog]

One of my primary teachers taught us that a, e, i, o and u aren't letters. They are vowels. It's a wonder I have an edjukashun.

 

[chroot]

I had a chemistry teacher who told the class that "a milliliter is a milligram." When I objected, and said that was only "true" (though not well-stated) for water at STP, she admonished "honey, a pound of feathers is a pound of lead." When I objected again, and said that a pound of feathers has a different volume than a pound of lead, she said "honey, a milliliter is the same as a milligram."

- Warren

 

[mrjeffy321]

Keep telling myself:

"be part of the solution..."

"be part of the solution..."

"be part of the solution..."

If your not part of the solution, your part of the precipitate.

 

[russ_watters]

Oh, dear lord, if we start catalogging the mistakes of my primary school teachers, we'll be here all day.

- Warren

Dude, I am here all day!

 

[russ_watters]

I had a math teacher in 7th grade that told us there was a year zero. Having just read about the history of the calendar in "3-2-1 Contact Magazine", argued with him, and he bet me a soda that there was. I showed him the magazine and he changed to 'uh, I meant a zero point'. Yeah, like I would have misunderstood that? He never did admit he was wrong, but I still got my soda.

 

[Cyrus]

My high school had ass crap for science classes. They were a joke, utterly utterly worthless. The only good thing offered was biology, and I was not interested. Makes for a sucky way to start engineering school, eh?

 

[DocToxyn]

I thought it was to eliminate the rubber perishing (oxidising) from the inside out. Obviously not a factor with car tyres, because for almost all users, they'll wear out before they age. For heavy duty and specialist tyres though, this is an issue.

Also, compressed nitrogen is dry, - compressed air will have a wetness fraction which can freeze, and can also expands a lot more with heat. I don't really buy this second argument, especially for the low pressures and low sensitivity on pressure for road use, but I suppose it's worth a thought for high performance and critical applications.


I suspect the real reason is that people saw race/rally teams using compressed nitrogen because it's more convenient, assumed that it offered a significant technical advantage, and copied them.

I'm with brewnog on this one. http://www.bentrideronline.com/messageboard/showthread.php?t=14247&highlight=nitrogen+tires"also came up on my recumbent bike forum, it gets a little geeky, but hey this is PF.

 

[Mattara]

My Biology teacher told the class that a species is two animals being able to re-produce last week (didn't mention fertile off-spring nor naturally re-producing).

I found enormous pleasure in correcting her .

 

[mrjeffy321]

I never had many problems with my science teachers' knowledge (although I have a sneaking suspicion that I know more chemistry than my old chemistry teacher now in some respects), now history teachers trying to incorporate science into their lesson…that’s a different story.

My brother on the other hand is always telling me stories about what his Physical Science teacher says during class. We suspect that she is only keeping 1 day ahead of the students she teaches. I have heard (amongst other things) that she has neglected to teach anything about the law of conservation of energy, nor does she know if/how Hydrogen atoms can bond with other atoms.

 

[matthyaouw]

I still remember how I was taught how an atom was the smallest thing ever.

I realize they were just simplifying things for our young little minds, but I was still tempted to shout profanities and objections at the teacher.

 

[FredGarvin]

The post about the aircraft using nitrogen was right on, but there is also one other aspect that was left out and that is ease of maintenance. N2 is used also because hydraulic accumulators are precharged with nitrogen as well. So it makes things easier for ground crews to have a single airsource than having to get two of them.

I have a very hard time believing the water argument. The outside of the tire is going to have a comperable amount of water in contact with the tire. So what doe that really buy you if you have a dry source inside the tire?

I got from the OP that the people that were doing this in an attempt to get better gas mileage or something akin to putting helium in a football.

 

[Astronuc]

Reading this stuff hurts to much

I was very fortunate because the key math and science teachers at my second high school had at least MS in their subjects. They taught college level.

The top level course was Math AP BC and we did elementary analysis, differential calculus and integral calculus in one year (3 trimesters) and I took 5 classes per trimester rather than the usual 4. I placed out of freshmen calculus in university.

The chemistry teacher has an MS in Chemistry and she was brilliant. Senior year I took a second year of chemistry (AP), and placed out of freshmen chem at university.

Physics was more problematic. My best friend took Physics in his junior year, and the teacher was a brilliant PhD from Caltech. My friend and I had him during a summer physics program at a local university. Unfortunately, he left the summer before I took Physics, and we ended up with a guy who was getting a Master's degree in teaching (ARRGGGHHH). He was not a very good physics teacher. I still placed out of part of freshmen physics at university.

The humanities teachers were another story. I got by in English classes since I really didn't care for literature, although the class in science fiction literature was great.

History, government and economics were a relative waste, but I did very well anyway.

 

[matthyaouw]

I remember reading a story on a website about a man who had a friend who was very proud of his posh private education, and snubbed those 'unintelligent' people who went to state schools. So "educated" he thought himself, and yet he would swear by such gems as:

"Hydrogen won't burn because it is the wet part of water"

 

[Geographer]

I find it quite bemusing how certain teachers don't know a considerable amount about their subjects. In the space of a few weeks, I'd already told 2 science teachers what an isotope is. Then again, these teachers are those who teach lower-level pupils (no excuse, really), and I've generally found that my own science teacher (set 1) knows his stuff with the exceptions of a few things; not that we can expect them to know everything, but when they clearly don't know things they should, then it becomes a problem. I've always thought they were qualified in their subjects... strange. I actually want to become a geography teacher, but, for the pupils' sake, I think I'd make sure I knew my stuff before stepping into the classroom.

Incidentally, I think the only teacher in my school with an MSc degree is my geography teacher, and she's great. Very meticulous (down to the last comma!) about what we write - for our sake, and she also took the time to come in today during holiday time in order for us to complete important coursework. That's a good teacher, in my opinion; not the ones that just go through the motions, so to speak.

[rambling/]

 

[pallidin]

From: http://www.trucktires.com/publications/periodicals/RealAnswers/03v8iss3/ra8.asp


Air is about one-fifth oxygen, and oxygen, especially at high temperatures and pressures, is a very reactive element.

When oxygen reacts with things, the process is called oxidation. When oxidation is extremely rapid, the process is called “burning.”

That’s one reason nitrogen is used in off-highway and aircraft tires. These tires run so hot they can actually catch on fire.

Nitrogen doesn’t support combustion, so nitrogen-filled tires don’t add fuel to the flames. And, nitrogen helps prevent slower forms of oxidation too.