Thread: Fahrenheit/Celsius

I have noticed that a number of posts give temperatures on the fahrenheit scale. These posts appear to originate in the US. The fahrenheit scale has almost disappeared in Europe. Is it still taught in American schools and is it the temperature scale that is used in such things as weather forecasts in the US?

The farenheit scale still has some relevance to science as the 0 in the scale falls on an important change of state of something(which I cant quite remember). Just like 0oC is the melting point of water at 1 barr and 0oK is absolute zero.

Yes it is. We do not have a clue about the Celsius scale over here, but they use it in Canada.

We also use feet, inches, gallons etc, although those danged foreign cars force us to buy a set of metric wrenches if we want to work on our cars. And for some reason we buy our soft drinks by the liter. Not sure why, because everything else is in ounces, pints, quarts and gallons.

I think 0 degrees F is the coldest you can make a mixture of ice and salt. I don't know about 100 F.

We also use feet, inches, gallons etc, although those danged foreign cars force us to buy a set of metric wrenches if we want to work on our cars.

Interesting stuff, Harold. It seems that the US is about fifteen years behind times. I have been to California, Nevada and Arizona (truly fascinating places -in fact, my favourite places) but, in some respects, it felt like going back in time with all those inches, pounds, and gallons. I also have a selection of wrenches with things like 9/16" written on them, but they are now obsolete here. I have to use a wrench with something like 13mm written on it if I seriously intend to service my car. It's ironic that some of these units originated in Britain but they now seem to be rescued from extinction by the US.

Even in England, its 12 years since I left school but we were taught in metric . Outside of school though, Its only been since the last couple of years that 1 law has been brought into place: Loose food has to be sold in kg's. Apart from that we are still mostly an imperial society with the metric option.

Ask a Brit for his height, weight and what he has delivered on his doorstep each morning!

Oh you are English. Dont you think we have a hell of a way to go to get fully metricized though?

GhostofMaxwell,

I agree that most people in the UK would give their height in feet and inches. We also have speed limits such as 30 miles per hour. But we are in a transitional phase. We could also be a bit ahead of the US in the transitional process. I think that the fahrenheit scale of temperature is now defunct here. Weather forecasts use Celsius and that scale now seems to be the norm. Petrol (gas) pumps specify volumes in litres rather than gallons and the dimensions of all my kitchen furniture is specified in millimetres. What is peculiar about this peculiar discussion is that if I write "millimetre", a red dotted line appears under it suggesting that it is a spelling mistake. But if I write "millimeter", all is OK. So the US doesn't seem to use millimetres, but it tells us how to spell them! :-D

I think you can probably change the default setting on your computer or whatever spell checker you are using to the British spelling.

I do recall back in about the 70s there was a move to convert to metric, but it wasn't very popular here. I guess we are cocky enough to think everybody else should do it our way. But gradually as manufacturing has moved abroad, we are slowly seeing more and more metric measures.

We do learn metric in science classes so we can use it if we need to. But we still do our engineering in feet, pounds and degrees F.

Originally Posted by Old Fool

I have noticed that a number of posts give temperatures on the fahrenheit scale. These posts appear to originate in the US. The fahrenheit scale has almost disappeared in Europe. Is it still taught in American schools and is it the temperature scale that is used in such things as weather forecasts in the US?

They usually use it to describe climate and weather, but in science classes they generally use the celcius and kelvin scales

Originally Posted by Harold14370

We also use feet, inches, gallons etc, although those danged foreign cars force us to buy a set of metric wrenches if we want to work on our cars.

remember what happen during the first space shuttle accident : i seem to remember it had something to do with the dimensions of the O-rings where the japanese supplier had designed in metric after conversion from the original american units

Originally Posted by marnixR

Originally Posted by Harold14370

We also use feet, inches, gallons etc, although those danged foreign cars force us to buy a set of metric wrenches if we want to work on our cars.

remember what happen during the first space shuttle accident : i seem to remember it had something to do with the dimensions of the O-rings where the japanese supplier had designed in metric after conversion from the original american units

I never heard about that. All I ever heard was that it was too cold for the o-rings to seal.

http://history.nasa.gov/rogersrep/v1ch4.htm

Conclusion
In view of the findings, the Commission concluded that the cause of the Challenger accident was the failure of the pressure seal in the aft field joint of the right Solid Rocket Motor. The failure was due to a faulty design unacceptably sensitive to a number of factors. These factors were the effects of temperature, physical dimensions, the character of materials, the effects of reusability, processing, and the reaction of the joint to dynamic loading

Ive heard something similar but related to a a deepspace probe/satelite malfunction, which is strange since I though NASA worked with the metric system even though the general population of the US is familiar with the archaic imperial system (I have to tease).

I look forward to the day when the US will get with the program and join the rest of the world community (learn/use metric the same way many people around the world learn english when their native language is something different, although I saw a US tv show in which someone goes door to door and gets 'no ingles' from people in the US that appear to not speak english at all while people on the other side of the world that arent even in or near an english speaking country can carry a basic conversation, which makes me think of the movie 'trains planes and automobles'... "you're going the wrong way!" ).

Who cares which system the U.S. uses for things like weather reports and speed limit signs? I think people who get their panties in a bunch over it should do a priority check.

Originally Posted by icewendigo

Ive heard something similar but related to a a deepspace probe/satelite malfunction, which is strange since I though NASA worked with the metric system even though the general population of the US is familiar with the archaic imperial system (I have to tease).

I look forward to the day when the US will get with the program and join the rest of the world community (learn/use metric the same way many people around the world learn english when their native language is something different, although I saw a US tv show in which someone goes door to door and gets 'no ingles' from people in the US that appear to not speak english at all while people on the other side of the world that arent even in or near an english speaking country can carry a basic conversation, which makes me think of the movie 'trains planes and automobles'... "you're going the wrong way!" ).

Originally Posted by Wikipedia on Mars Climate Orbiter

The metric mixup

The Mars Climate Orbiter’s reaction wheels were kept within their linear (unsaturated) range through thruster firings in a procedure called Angular Momentum Desaturation (AMD). When an AMD event occurred, relevant spacecraft data was telemetered to the ground, processed, and placed into a file called the AMD file. The JPL operations navigation team used data derived from the AMD file to model the forces on the spacecraft resulting from these specific thruster firings. Modeling of these small forces is critical for accurately determining the spacecraft’s trajectory. Immediately after the thruster firing, the velocity change ("delta-V") is computed using the firing time for each of the thrusters, and an impulse bit, which models each thruster's performance. The calculation of the thruster performance is carried out both on-board the spacecraft and on ground support computers. The flight software installed on the spacecraft correctly computed the velocity change and transmitted it to earth. The ground software, however, was originally written for the Mars Global Surveyor (MGS) mission, and the MGS flight software did not compute nor transmit velocity change information. The ground software, then, discarded the transmitted velocity change and recomputed it. Since the Mars Climate orbiter used a differently-sized thruster than Mars Global Surveyor, an update to the thruster equation in the ground software was necessary. The conversion factor from pound-seconds to newton-seconds was buried in the original equation and not immediately identifiable, and so it was not included in the updated equation. Thus, the ground software reported calculated "impulse bits" which were a factor of 4.45 too large (1 pound force = 4.45 newtons). Subsequent processing of the calculated impulse bit values from the AMD file by the navigation software underestimated the effect of the thruster firings on the spacecraft trajectory by this factor.

This mixup was exacerbated by two factors:

The lack of end-to-end testing of the AMD data flow before launch
The lack of an independent navigation algorithm to cross-check the AMD-based algorithm in flight
Both had been performed on previous missions, but deleted from the MCO plan due to budget cuts.

BTW, Fahrenheit temperature scale is as piss-poor as it can be. Fahrenheit chose as 0 and 100 the coldest temperature he could achieve (mixing salt and ice) and as 100 human body temprature. As temperature of salt-ice mixes depends upon mix ratio and time and human body temperature changes from a person to the next one, Fahrenheit scale is based upon arbitrary and hardly repeatable events...

Celsius scale is based upon water freezing temperature (0ºC) and boiling temperature (100ºC)... which are easier to standarize.

Originally Posted by Lucifer

BTW, Fahrenheit temperature scale is as piss-poor as it can be. Fahrenheit chose as 0 and 100 the coldest temperature he could achieve (mixing salt and ice) and as 100 human body temprature. As temperature of salt-ice mixes depends upon mix ratio and time and human body temperature changes from a person to the next one, Fahrenheit scale is based upon arbitrary and hardly repeatable events...

Celsius scale is based upon water freezing temperature (0ºC) and boiling temperature (100ºC)... which are easier to standarize.

First of all, you don't know if this is how he calculated his scale or not. There's a bunch of stories on that. Second, it's irrelevant to the usefulness of the scale.
0 F is really cold, and 100 F is really hot. From an intuitive standpoint it's a great scale for temperature and weather and let's face it, that's the only thing 99% of people care about. I don't think people give a shit if their water boils at 100 or at 212.

Originally Posted by Neutrino

From an intuitive standpoint it's a great scale for temperature and weather and let's face it, that's the only thing 99% of people care about. I don't think people give a shit if their water boils at 100 or at 212.

The Fahrenheit scale works perfectly well in engineering, too. Get a set of steam tables in degrees F and psi, and you can design a power plant just fine.
I think the scale was changed to define 32 as the freezing point, and 212 as boiling, so the original definitions don't matter much today. It is handy to know that your rock salt won't work to melt ice on the sidewalk below 0 F.
The main problem, really is compatibility with the rest of the world. Even that is not so important when we can make unit conversions with a few strokes on the computer keyboard.

Originally Posted by Neutrino

Originally Posted by Lucifer

BTW, Fahrenheit temperature scale is as piss-poor as it can be.
Celsius scale is based upon water freezing temperature (0ºC) and boiling temperature (100ºC)... which are easier to standarize.

First of all, you don't know if this is how he calculated his scale or not. There's a bunch of stories on that. Second, it's irrelevant to the usefulness of the scale.
0 F is really cold, and 100 F is really hot. From an intuitive standpoint it's a great scale for temperature and weather and let's face it, that's the only thing 99% of people care about. I don't think people give a shit if their water boils at 100 or at 212.

First of all........it's just the Americans using this kinda useless piece of crap temperature scale and I definitely have to second Lucifer: it IS as piss poor as it gets. (Just like all the other arbitrary BS like feet and the like) And the way he set up his scale is just the way Lucifer describes it. And for Celsius: well it is not as good as people wanna make you believe. The phase transformation temperatures for the most common solvent on earth are not exactly stable, they also depend on the pressure of the surroundings. And yes, this is still way better than F. The only real scale however is K and no, it is not °K it's just K.

Oh yeah that's a great suggestion. Let's use Kelvin.
Hey folks it's 250 out today, bundle up! That's a cold one!
That makes tons of sense.

Im thinking of setting up my own scale called Jason where 0 corresponds to the melting point of girls hearts. :-D

Originally Posted by Neutrino

Oh yeah that's a great suggestion. Let's use Kelvin.
Hey folks it's 250 out today, bundle up! That's a cold one!
That makes tons of sense.

Well, I was not suggesting to use it in everyday life. It's too much of a hassle to get people used to something new anyway. I just stated the fact that C is not the most accurate scale either. And for thermodynamics: in some equations it's hard to use Celsius anyway

Well i finished school 10 years ago and remember being taught both Celsius and Fahrenheit. One thing that really does get on my nerves though is when the weather people use Celsius for the winter temperatures and Fahrenheit for the summer.

In science class in school we used C and K. On the weather report on TV we use F. Isn't a big deal

Yep, it's just something of a pet peeve for me, trying to make the temperatures (or anything) seem more impressive than it is.