/sci/ - Science & Math » Thread #14000834

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Cant convert from Celsius to Fahrenheit. WTF?

Anonymous Thu 23 Dec 16:34:19 2021 No.14000834 View Reply Original Report

Quoted By: >>14000838 >>14000843 >>14000844 >>14000870 >>14000881 >>14000921 >>14000937 >>14000998 >>14001288

Ok bros I am American and I don't understand Celsius so I want to convert to Fahrenheit. I get this sentence.

>El Niño refers to a phenomenon in which the sea surface temperature near the equator rises by 1 to 3°C.

And I know that f = 9c/5 + 32.

Since I know T is a delta temp I have

T = Tnew - Told

And converting to F I get

Tf = 9Tnew/5 + 32 - 9Told/5 - 32 = 9T/5

But if I just naively converted T from C to F then I would get

Tf = 9T/5 + 32

But 9T/5 + 32 = 9T/5!

Ok this may all seem trivial but all I did was subtract so my units didn't change? So what happened here? How do I keep track of these units? What if I wanted to write a program that did unit conversions? What's going on here?

Anonymous

Anonymous Thu 23 Dec 2021 16:36:53 No.14000838 Report

Quoted By: >>14000845

>>14000834
Here's what you do
>type in google 1c to fahreheit
>type in google 3c to fahreheit
>learn to say "Do you want fries with that" with gusto

Anonymous

Anonymous Thu 23 Dec 2021 16:38:46 No.14000843 Report

Quoted By: >>14000847

>>14000834
>T is a delta temp I have
>delta temp
You just need to scale. No need for the offset. Do you not understand how linear transformations work?

Anonymous

Anonymous Thu 23 Dec 2021 16:38:58 No.14000844 Report

Quoted By:

>>14000834
The absolute state of amerifats

Anonymous

Anonymous Thu 23 Dec 2021 16:39:16 No.14000845 Report

Quoted By: >>14000856

>>14000838
Yea, it gives the wrong answer if you do that - the 32's don't cancel. Do you understand?

Anonymous

Anonymous Thu 23 Dec 2021 16:40:25 No.14000847 Report

Quoted By: >>14000854 >>14000998

>>14000843
>Do you not understand how linear transformations work?

Like T(ax + by) = aT(x) + bT(y). I know this.

Anonymous

Anonymous Thu 23 Dec 2021 16:41:31 No.14000854 Report

Quoted By: >>14000878

>>14000847
Anon, how many F is one C? What does the 9/5 mean?

Anonymous

Anonymous Thu 23 Dec 2021 16:42:03 No.14000856 Report

Quoted By:

>>14000845
>Do you understand?
No, do you want fries, not if he understands

Anonymous

Anonymous Thu 23 Dec 2021 16:43:57 No.14000862 Report

Quoted By:

>It's another /sci/ attempts to do high school math homework for anon
I hate reruns

Anonymous

Anonymous Thu 23 Dec 2021 16:46:01 No.14000870 Report

Quoted By:

>>14000834
The constant is in burger units too

Anonymous

Anonymous Thu 23 Dec 2021 16:47:03 No.14000878 Report

Quoted By: >>14000998

>>14000854
9/5 = dF/dC

But my units! My units didn't change! So what is changing that I can keep track of whether it's an absolute or delta temp?

Again I know this seems simple and dumb but what is going on here? How do people deal with this? These things have different "types".

Anonymous

Anonymous Thu 23 Dec 2021 16:47:34 No.14000881 Report

Quoted By: >>14000890 >>14000905 >>14000998

>>14000834
I don't understand where your confusion is.

F = 9c/5 + 32
Told = 9(1)/5 + 32
Told = 33.8
Tnew = 9(3)/5 + 32
Tnew = 37.4

Tnew - Told = 3.6

Or if you'd prefer to do it all in one equation:
9(3)/5 + 32 - (9(1)/5 + 32) = Tdelta
5.4 + 32 - 1.8 - 32 = Tdelta
3.6 = Tdelta

Or you could just remember that each delta of 1 degree C is equivalent to a delta of 1.8 degrees F.

Anonymous

Anonymous Thu 23 Dec 2021 16:49:10 No.14000889 Report

Quoted By:

>the absolute state of burgers

Anonymous

Anonymous Thu 23 Dec 2021 16:49:36 No.14000890 Report

Quoted By:

>>14000881
Thanks. I will put it down in my homework and hand it in

Anonymous

Anonymous Thu 23 Dec 2021 16:54:08 No.14000905 Report

Quoted By: >>14000922 >>14000960 >>14000998

>>14000881
I guess the confusion is say I say something is X deg C and it has increased in temperature by Y deg C and I want to convert these to F. But I have 2 different formulas!

Xf = 9X/5 + 32
Yf = 9Y/5

I understand why these formulas are different but what I don't understand is the units. Both X and Y have the same units, deg C, but they have different "types" hence the use of different formulas. What is this type. Bro maybe I am dumb but what am I missing here?

Anonymous

Anonymous Thu 23 Dec 2021 16:54:56 No.14000907 Report

Quoted By:

Anons, I hope you realize that
>rises by 1 to 3°C
is not the same as
> rises from 1°C to 3°C

Anonymous

Anonymous Thu 23 Dec 2021 16:56:48 No.14000916 Report

Quoted By:

Like what if I wanted to program this and I had some temperature type. I would also need some delta temperature type as well? If I wanted to be able to arbitrarily change units?

Anonymous

Anonymous Thu 23 Dec 2021 16:58:12 No.14000921 Report

Quoted By:

>>14000834
>look at me I'm a retard

Anonymous

Anonymous Thu 23 Dec 2021 16:58:21 No.14000922 Report

Quoted By: >>14000948

>>14000905
one is for temperature
the other is for temperature difference
>35 °C is 95°F
>a difference of 35 °C is 63 °F

Anonymous

Anonymous Thu 23 Dec 2021 17:01:27 No.14000937 Report

Quoted By:

>>14000834
It's too much work, just use google or some tool as others say.

Anonymous

Anonymous Thu 23 Dec 2021 17:04:06 No.14000948 Report

Quoted By: >>14000964 >>14000998

>>14000922
But the units do not capture this information. Adding and subtracting does not change the units.

Same issue with energy. Delta energy is not the same as energy. Obviously because these things do not share the same point at 0 like lots of other measurements like length, time, etc.. which have different units but 0 equals 0 in all units.

There is some fundamental difference here where I have to keep track of not only units but whether it's a delta or not. Something I do not have to do for changing length units.

What's the deal here? How am I supposed to be capturing this information other than just noting it in my head?

Anonymous

Anonymous Thu 23 Dec 2021 17:08:00 No.14000960 Report

Quoted By: >>14000998 >>14000999

>>14000905
When you want to convert inches to feet, you use the formula:
feet = inches/12
or
inches = feet * 12
so 8ft = 96 inches
and 0ft = 0 inches

If I asked "Bob grew from 2 feet to 4 feet, how many inches did bob grow?"
You could subtract 4-2 = 2 feet grown, then multiply by 12 to say that he grew 24 inches.

Imagine if what we call 0 feet was actually 24 inches, but each foot still consists of 12 inches. If the 0s for both units started at different places, but the conversion factor of 12 still existed. In this world, 0 inches would be -2 feet. One foot would be 36 inches, two feet would be 48in, etc.

In this world, the equation to convert from feet to inches would be:
inches = (feet*12) + 24
And to go backwards the formula would be:
feet = (inches-24)/12

If I asked again "Bob grew from 2 feet to 4 feet, how many inches did bob grow?"
And you did the same as before, subtracting 4-2 = 2 feet grown, then used our new formulas for converting that 2 feet to inches, you would have:
(2*12)+24 = 48 inches

Why is the answer incorrect now? I think if you mull it over you'll come to a better understanding.

Anonymous

Anonymous Thu 23 Dec 2021 17:08:29 No.14000964 Report

Quoted By:

>>14000948
You don't have to do it for length but you have to do it for positions. Lengths measure differences in positions

Anonymous

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Anonymous Thu 23 Dec 2021 17:18:34 No.14000998 Report

Quoted By:

>>14000834
>>14000847
>>14000878
>>14000881
>>14000905
>>14000948
>>14000960
>reddit spacing

Anonymous

Anonymous Thu 23 Dec 2021 17:19:23 No.14000999 Report

Quoted By: >>14001280

>>14000960
Bro I fundamentally understand that there is a transform of the form

T(x) = ax + b

to go from one unit to another. And if you have the 0 of every unit be the same then you have T(0) = 0 and so you must have b=0 and so you get these easy unit conversions where you don't need to worry about whether you are taking a delta or not.

But in the case that some value in some unit is 0 and in a different unit it is not 0 then you all of a sudden have to keep track of whether you are working with some absolute quantity or a delta quantity. But - and I am an 2nd year undergrad so im not smart - everyone seems to just kind of assume you will deal with this without problems and I get it and everything. But still what is going on. I get it mathematically but again what if I wanted to program it and I wanted a temperature type and I wanted a function to do conversions from C to F but then if I did a subtraction between two temperatures I would have to make a new type, a delta temperature, otherwise if I use my conversion function it would be wrong.

How do people normally deal with this formally and shit?

Anonymous

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Anonymous Thu 23 Dec 2021 18:24:48 No.14001280 Report

Quoted By: >>14002523

>>14000999
>but then if I did a subtraction between two temperatures I would have to make a new type, a delta temperature, otherwise if I use my conversion function it would be wrong

Anonymous

Anonymous Thu 23 Dec 2021 18:28:04 No.14001288 Report

Quoted By:

>>14000834
just fucking use google and work your way backwards inbred amerishit retard
>the absolute state of american education

Anonymous

Anonymous Fri 24 Dec 2021 00:07:26 No.14002523 Report

Quoted By:

>>14001280
Yea but what if I found the delta in C and then later I decided I wanted to change it to F. At that point I would have to know it was a delta temperature. If someone just said 2 deg C then that wouldn't be enough to do the conversion because they would have to say a 2 deg C delta, not absolute.

I took Chem and Physics and we even went over unit conversion. Like a whole day and they would go over canceling and shit but it would always be multiplying by some ratio.

But here we have some value with several different units where the 0 point is not the same in every unit. So now there is something fundamentally different. I am no longer just scaling to get a different unit, but doing a more complicated action of using some function that maps an interval in C [0, 100] to an interval the interval in F [32, 212] to do a unit conversion. Since I have to do this more complicated unit conversion I have to keep track of whether values are absolute or deltas. This info doesn't seem to be carried in the units which do not seem to change under subtraction. Something is fucked.

Again I understand the math. It's trivial. I just don't understand if this is formalized somewhere or what? Am I the only one who notices this? What if I want to program. What is the type of X-Y for temperatures X and Y? If I make the type temperature then try to convert it will be wrong. So obviously I need some type like delta temperature or something to convey this information.

It's not that calculation I have trouble with it's the concept itself. No one that has a unit conversion library seems to take delta temps or have this type so how are they tracking this info?

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