Fizikia: Joto (chemsha bongo!)

[SMU]

hii umeipataje kiongozi?

Nilipeleka kwenye kipimo cha kelvin, kuzidisha na kisha kurudisha kwenye centigrade!

 

[SMU]

Ni hv!vpm vya joto vyote vp ktk ratio scale,na moja ya sifa kubw ya vpm hv n kwmb hvn absolute zero,so haviwez kuzidishwa!

Lakini kwa kipimo cha kelvin kuna absolute zero(at least from thermodynamic point of view)! So baridi mara mbili ya 0 deg centigrade naamini itakuwa kama -136.5 deg centigrade!

 

[Gaijin]

kwa physics point of view, upimaji wa joto (baridi) unategemeana na energy kwenye kimiminika (in this case air) kinachopimwa. Kwa hiyo lazima tuangalie masuala ya absolute zero kama alivyosema SMU hapo juu.

Kama tutahusisha na absolute zero basi tutalazimika kubadili kwenda kwenye Kelvin kwanza kisha ndo kurejesha kwenye Celsius.

Twice as cold as 0 Centigrade is -136.58 Cenrigrade )

 

[ngoko]

Kama baridi ya leo ni nyuzijoto sifuri na tunatarajia kesho kutakuwa na baridi mara mbili ya hii ya leo, je baridi ya kesho itakuwa nyuzijoto ngapi?

Remember Zero degree (can be C, F , K etc) is just a point of reference in relation to a given temperature scale , so manipulation can always be done to arrive at the correct value ( usichanganye na wazo la kwamba n times zero = zero, temperature calculations does not behave like that) . anyway that is my personal view

 

[Sikonge]

Sina muda kwa leo ila nafikiri utakuwa umefanya makosa kwenye mahesabu yako.

Hapa unaweza kuwa umetumia PURE Mathematics katika kugawanya na kuzidisha.

Ukweli unaweza kuwa kwamba, ulitakiwa kufanya INTERPOLATION.

Kwenye kubadili Units, inabidi pia uwe mwangalifu mwanawane........

Mara mbili ya Unit X, inaweza isiwe mara mbili ya Unit Y. Interpolation inamaliza ubishi.

Lakini kwa kipimo cha kelvin kuna absolute zero(at least from thermodynamic point of view)! So baridi mara mbili ya 0 deg centigrade naamini itakuwa kama -136.5 deg centigrade!

 

[Kiranga]

 

[ZeMarcopolo]

Kiranga, ushajipigia kura?

 

[Mtazamaji]

Hii chemsa bongo imenitoa kapa . lakini imeufanya ubongo wangu uwe active kwa kufikiria possible answers ambazo hata hivyo nilikuwa wrong.

Kuna wataalama wengine wanatoa majibu haya

Hello, and thanks for writing to Dr. Math. You pose a very interesting question. What is the temperature if it's twice as cold as zero degrees? The Fahrenheit and Celsius temperature scales are "relative" temperature scales, in that they are both relative to a couple of specific temperatures, namely the freezing and boiling points of water.

Let's make your question a little more specific: "What is the temperature if it's twice as warm as 0 degrees Celsius (the freezing point of water)?" To answer this question we need to convert this Celsius temperature to an "absolute" temperature scale, a scale with no negative temperatures. We'll use the Kelvin scale.

0 degrees Kelvin is the point at which all motion in matter stops; it is known as "absolute zero." No temperature can exist that is lower than 0 degrees Kelvin. The formula to convert from Celsius to Kelvin temperature is K = C + 273.15, where K is the Kelvin temperature and C is the Celsius temperature.

So 0 degrees Celsius is equal to 273.15 degrees Kelvin. We can double this number to get 546.30, the temperature that is twice as warm as 0 degrees Celsius.

We can then subtract 273.15 from our answer to convert it back to the Celsius scale. The temperature is 273.15 degrees Celsius when it is twice as warm as 0 degrees Celsius. Makes perfect sense, doesn't it? ..............................

source Math Forum - Ask Dr. Math

Sasa huyu ndio alikaribia kunichanganya mwanzoni ila baadaye nikmuelewa

There is no really good answer to this question; the term "twice as cold" is not well defined. A physicist might want to define it one way, but someone deciding what to wear would have good reason for defining it in a very different way.

To the best of my knowledge, no one has actually defined it quantitatively, in either of these ways or any other way. Still, I will tell you my ideas on two ways "twice as cold" *could* be defined if you insisted on doing so. "Cold" is confusing in the same way that "short" or "small" is confusing. If I say that I am twice as short as you, what I probably mean is that I am half as tall as you. It isn't really a good way to talk at all; it's best to say "half as tall" because it's less confusing.

"Cold" is even more confusing than "short" because temperatures can be negative, but height can never be negative (not the height of a person, anyway). If "twice as cold" means "half the temperature", then if the temperature is negative, "twice as cold" is *warmer*! For instance, half of -10 degrees is -5 degrees, which is warmer than -10 degrees. If "twice as cold" meant "twice the temperature", it would go in the right direction for negative temperatures, but not for positive temperatures.

Then, too, there's the problem that "twice as cold" will mean different things depending on whether you are using the Celsius or Fahrenheit scale. "Twice as cold" as 0 C is 0 C, but 0 C is 32 F, and half of this is 16 F, which is -8.9 C. One solution is to choose a meaningful zero point for temperature.

Physicists determined that temperature has to do with how much energy there is in the air (or whatever you're taking the temperature of.) This energy is all gone when you get down to a temperature of -273.15 degrees Celsius, or about -460 degrees Fahrenheit. This temperature is called "absolute zero."

The scientists then invented two new temperature scales: Kelvin, which is the degrees C plus 273.15, and Rankine, which is the degrees F plus 460. That means that 0 degrees on either scale is absolute zero. Therefore I propose that if you insist on saying "twice as cold," we should mean this by it: "half the temperature on the Kelvin (or Rankine) scale." By this definition, "twice as cold as 0 C" is half of 273.15 K, which is 136.57 K. Converting this back to Celsius, we get -136.58 C. That's very cold. I don't think it will ever be "twice as cold as 0 degrees" in either Fahrenheit or Celsius.

This definition of "twice as cold" might satisfy a low-temperature physicist, who is concerned about the amount of energy in a substance, but it does not agree with our everyday idea of cold. Our everyday use of "twice as cold" might be something like, "It's so cold that I need to wear twice as much clothing."

If I wanted to invent a mathematical meaning for "twice as cold" that would fit this idea, I would pick a temperature that is neither warm nor cold, perhaps 65 F. Then "how cold it is" would mean "how many degrees below 65 F," and "how hot it is" would mean "how many degrees above 65." Then 45 F would be "twice as cold" as 55 F, and -65 F would be twice as cold as 0 F. (That's still very cold!) You can see that this is a very different definition from the first one.

It makes more sense according to our everyday idea of cold, but it has one problem: some international agency has to set that "neither cold nor warm" temperature. Judging from the battles some families have over thermostat settings, I don't think this will be easy! So I say again, I would rather avoid the phrase "twice as cold" altogether.

So kichemsha bongo sikuwa na jibu. but ubongo umechemka na kuwa active. na gaijin naona ni mtaalam

 

[Kiranga]

Kiranga, ushajipigia kura?

Kujipigia kura wapi? Principles zangu zinaona kujipigia kura kama kuna conflict of interest vile. Vipi kwani?

 

[Kiranga]

kwa physics point of view, upimaji wa joto (baridi) unategemeana na energy kwenye kimiminika (in this case air) kinachopimwa. Kwa hiyo lazima tuangalie masuala ya absolute zero kama alivyosema SMU hapo juu.

Kama tutahusisha na absolute zero basi tutalazimika kubadili kwenda kwenye Kelvin kwanza kisha ndo kurejesha kwenye Celsius.

Twice as cold as 0 Centigrade is -136.58 Cenrigrade )

Sioni umuhimu wa kuingiza absolute zero wakati ushapewa joto kama 0 C, kuingiza absolute zero kuta serve purpose gani mtaalamu wangu?

 

[Mtazamaji]

Sioni umuhimu wa kuingiza absolute zero wakati ushapewa joto kama 0 C, kuingiza absolute zero kuta serve purpose gani mtaalamu wangu?

Nadhani purpose of absolute zero temperature ni kuondoa complication zinazoletwa na positive and negetaive reading. pamoja na F and C conversion.

 

[Mtazamaji]

Kimahesabu na physics gaijin yukosahii lakini kuna hii comment ya jamaa pia ina ukweli

" By this definition, twice as cold as 0 C" is half of 273.15 K, which is 136.57 K. Converting this back to Celsius, we get -136.58 C. That's very cold. I don't think it will ever be "twice as cold as 0 degrees" in either Fahrenheit or Celsius.

Je ukiweka theory za physcis na hesabu pembeni ni kweli practically -136.58 C ndio mara mbili ya 0 C. ??????!!!!!!!

Hapa nashindwa kuchanganyikiwa

 

[Sikonge]

Zero°C ni kama Benchmark kwenye mambo ya Ujenzi, Survey au Geografia. Hii point ijulikanayo pia kama POINT OF REFERENCE, huwa inachukua vitu kama urefu wake kutoka usawa wa bahari, umbali kutoka sehemu hiyo kwenda nyingine nk...

Sasa ukija kwenye 0 °C, hii ni kama Point of Reference katika mambo ya MOTO vs BARIDI. Vitu vyote vinaanzia hapa. Ukitaka kupima kitu chochote joto lake, basi unaanzia hapa. Ukisikia -X °C, basi unafahamu kuwa ni units X kutoka kwenye 0 kushuka chini na ukisikia +Y °C basi unafahamu kuwa units Y kutoka 0 kupanda juu. Hii ni point of reference na huwezi tena kuigusa katika kupima kwako.

Kwa Dar, Point of Refence ipo pale kwenye Mnara wa Saa. Sasa hapo ndipo siku zote wanaanza kupima umbali kutoka Dar es salaam kwenda mikoani na hata nchi nyingine duniani. Swali lako SMU ni sawa na kutaka kujua umbali kutoka hiyo Point kwenda kwenye hiyo point ukizidisha mara mbili ambapo jibu utapata ni Zero.

Ili kuthibitisha hilo jibu kuwa itakuwa 0°C na kubaki pale kwani hii ni Benchmark, tuangalia hii hesabu hapa chini:

Tufanye kwenye -1°C mara mbili itakuwa -2°C............. -0.00005°C mara mbili yake itakuwa -0.00010°C
Kwa kuangalia tabia yake hii, baridi inavyokaribia 0°C, basi mara mbili yake pia inakaribia 0°C.

 

[Gaijin]

Sioni umuhimu wa kuingiza absolute zero wakati ushapewa joto kama 0 C, kuingiza absolute zero kuta serve purpose gani mtaalamu wangu?

Temperature is a relative term, na madamu tukipima temperature ni sawa na kusema tunapima " the energy content in the fluid" inatulazimisha tuende kwenye reference point ya energy kwenye fluid ambayo ni absolute zero when there is no energy, ili tupate kulinganisha joto (baridi) la sasa ni kiasi gani (how much energy is there compared to when there is no energy at all)

Since absolute temperature is at 0 Kelvin then we should do the conversions into Kelvin first before we change back to Centigrade.

Je ukiweka theory za physcis na hesabu pembeni ni kweli practically -136.58 C ndio mara mbili ya 0 C. ??????!!!!!!!

Hapa nashindwa kuchanganyikiwa

Sasa practically ndio kitu gani wakati jibu ndo hilo ushapewa la uhakika.

Tatizo ni kuwa hakuna physicist yoyote atakaetaka kujua "how cold is twice as cold as 0C". Ni suala ambalo halina mantiki katika physics.

Suala lina mantiki kwa layman ambao katika mazungumzo yetu utatusikia "kesho baridi mara mbili ya leo" lakini tunachofikiri hasa ni "kesho tutalazimika kuvaa nguo mara mbili ya hizi za leo" kwa sababu tunapima baridi kwa hisia (au nguo)

Sasa labda suala liwe "tukisema tutalazimika kuvaa nguo mara mbili ya leo ambayo ni 0C, itakuwa C ngapi?"

Which will take us to the physics of heat tranfer and thermal resistance

 

[Gaijin]

Zero°C ni kama Benchmark kwenye mambo ya Ujenzi, Survey au Geografia. Hii point ijulikanayo pia kama POINT OF REFERENCE, huwa inachukua vitu kama urefu wake kutoka usawa wa bahari, umbali kutoka sehemu hiyo kwenda nyingine nk...

Sasa ukija kwenye 0 °C, hii ni kama Point of Reference katika mambo ya MOTO vs BARIDI. Vitu vyote vinaanzia hapa. Ukitaka kupima kitu chochote joto lake, basi unaanzia hapa. Ukisikia -X °C, basi unafahamu kuwa ni units X kutoka kwenye 0 kushuka chini na ukisikia +Y °C basi unafahamu kuwa units Y kutoka 0 kupanda juu. Hii ni point of reference na huwezi tena kuigusa katika kupima kwako.

Kwa Dar, Point of Refence ipo pale kwenye Mnara wa Saa. Sasa hapo ndipo siku zote wanaanza kupima umbali kutoka Dar es salaam kwenda mikoani na hata nchi nyingine duniani. Swali lako SMU ni sawa na kutaka kujua umbali kutoka hiyo Point kwenda kwenye hiyo point ukizidisha mara mbili ambapo jibu utapata ni Zero.

Ili kuthibitisha hilo jibu kuwa itakuwa 0°C na kubaki pale kwani hii ni Benchmark, tuangalia hii hesabu hapa chini:

Tufanye kwenye -1°C mara mbili itakuwa -2°C............. -0.00005°C mara mbili yake itakuwa -0.00010°C
Kwa kuangalia tabia yake hii, baridi inavyokaribia 0°C, basi mara mbili yake pia inakaribia 0°C.

Uko on point kwenye point of reference, but in energy and temperature physics the point of reference is 0Kelvin and not 0Centigrade.

 

[Mtazamaji]

Sasa practically ndio kitu gani wakati jibu ndo hilo ushapewa la uhakika.

G My dearest JF woman of the year 2010 .Teh Teh Teh

Ukiondoa Physics na Hizo hesabu najaribu kuhisi kama kweli ubaridi wa -136 C ndio mara mbili ya ubaridi wa 0 C

 

[Gaijin]

Ukiondoa Physics na Hizo hesabu najaribu kuhisi kama kweli ubaridi wa -136 C ndio mara mbili ya ubaridi wa 0 C

Haingii akilini ee!

Sayansi kaa inatudanganya hivi!

 

[Kiranga]

Absolute zero is a big myth, there is nothing absolute in this world, even the notion that there is nothing absolute is not absolute.

Of course Absolut Vodka is an exception that proves the rule. That is why it lacks the last e.

 

[Moseley]

Kama baridi ya leo ni nyuzijoto sifuri na tunatarajia kesho kutakuwa na baridi mara mbili ya hii ya leo, je baridi ya kesho itakuwa nyuzijoto ngapi?

Majibu:

1. nyuzi joto sifuri ( 0 centigrade)

0 centigrade ni sawa na 32 Fahrenheit.. Mara mbili ya 32 ni 64 Fahrenheit.. Ukibadilisha 64F kwenda kwenye centigrade inakuwa ni 18 Centigrade..
Kwa hiyo mara mbili ya 0 Centigrade ni 18 Centigrade.

2. nyuzi joto sifuri ( 0 Fahrenheit )



0 Fahrenheit ni sawa na -18 Centigrade.. Mara mbili ya -18C ni -36C. Ukibadilisha -36 kwenda kwenye Fahrenheit inakuwa ni -33 Fahrenheit..
Kwa hiyo mara mbili ya 0 Fahrenheit ni -33 Fahrenheit.


Kama swali lako lilihusisha CENTIGRADE, jibu ni lile la namba 1, na kama ulihusisha FAHRENHEIT jibu ni lile la namba 2

 

[Kiranga]

Majibu:

1. nyuzi joto sifuri ( 0 centigrade)

0 centigrade ni sawa na 32 Fahrenheit.. Mara mbili ya 32 ni 64 Fahrenheit.. Ukibadilisha 64F kwenda kwenye centigrade inakuwa ni 18 Centigrade..
Kwa hiyo mara mbili ya 0 Centigrade ni 18 Centigrade.

2. nyuzi joto sifuri ( 0 Fahrenheit )

0 Fahrenheit ni sawa na -18 Centigrade.. Mara mbili ya -18C ni -36C. Ukibadilisha -36 kwenda kwenye Fahrenheit inakuwa ni -33 Fahrenheit..
Kwa hiyo mara mbili ya 0 Fahrenheit ni -33 Fahrenheit.

It depends on what do you mean by "baridi mara mbili". Kama unaongelea mara mbili ya vipimo 0 C haitakusaidia kwa sababu 0 times anything is zero, and even conversion is meaningless, so you must be talking about energy levels. Kama unaongelea energy levels - which is what temperature ultimately is - it gets more involved than the simple conversion above. One could be misled to argue the above assertion is correct kwa sababu tumeambiwa 0 C. Lakini convertion ya C to F ina kutoa na kuzidisha, kwa hiyo a simplistic converion and halving will not be right.

Simple conversion zitatuambia kwamba

2 C = 36 F

Therefore 4 c, which is 2 x 2 C, must be equal to 36 F x 2, therefore 4 C must be 72 F

While actually 4 C = 39 F

I see where Gaijin is coming from with absolute zero as a theoretical tool. Baridi mara mbili zaidi means the energy will be halved.

Kama baridi mara 2 ya 0C ni halving the energy level, then it equals 0 + (-273.15 c)/2 which iS = - 136.575 c

Interestingly enough, the symmetry of K and C runs through the number 136.75 with 136.575 K = - 136.575 C

It makes more sense gauging this visually.