Why exactly Is Iron cooler than it's environment at 20°c?

sophiecentaur

It all depends what you require for your 'Science Education' and 'Science Progress'. I thought that Science progressed by reducing things to their simplest possible model. This excludes giving inanimate objects a will or the ability to choose.
The history of Science is very interesting but we have had several paradigm shifts since the Greeks and The Enlightenment to help us with our progress.
"Nature abhors a vacuum" is about as helpful a statement as "Things naturally fall down". Newton and subsequent Scientists have improved, somewhat, on that way of looking at things. I can't recall having read any recent text books or published papers in which we find things describes as "trying to do" anything.

I guess it's basically down to personal preference and to how interested one is in an objective, rather than a subjective appreciation of Science.

Buckleymanor

Taken as an isolated statement "Nature abhors a vacuum" is pretty useless the problem is when I see this statement I don't see nature doing anything what I imagine is two teams of horses and a large sphere.The horses are attached to the sphere by chains and trying to pull the sphere apart which is in two halves with the air sucked out of it.
So sure it becomes subjective to a point but it also makes the subject alive and exciteing.
I don't see no reason why there can't be a mixture of the preferences provided inanimate objects remain just that.

sophiecentaur

Quote by Buckleymanor

Taken as an isolated statement "Nature abhors a vacuum" is pretty useless the problem is when I see this statement I don't see nature doing anything what I imagine is two teams of horses and a large sphere.The horses are attached to the sphere by chains and trying to pull the sphere apart which is in two halves with the air sucked out of it.
So sure it becomes subjective to a point but it also makes the subject alive and exciteing.
I don't see no reason why there can't be a mixture of the preferences provided inanimate objects remain just that.

Have you ever had to salvage some sense out of a statement made by a 14 year old who needs to get a Science education and has been exposed to 1. TV Science fiction, 2. Simulations in computer games, 3. Religious Fundamentalism 4. Anthropomorphic Primary School Science teaching?
Of course, Science is 'ooh aah' exciting but getting it as near right as you can is even more 'ooh aah' exciting.

Buckleymanor

Oh! I see now why the distaste.You have an uphill task on your hands with little or no thanks.
I am not a teacher though I am married to one, whose mother was a teacher and her mother and her mothers sisters were also teachers.In other words the whole of her family is in some way connected to education.So one way or another I get regular updates of some of the problems they face.
Haveing children around the age of 14 and being married to a teacher makes me appreciate just how difficult your task is.
Sorry if I have contributed in a negative way.

sophiecentaur

I don't teach any more but I see you are getting my point. I regard this forum in much the same way as I saw School. Rigour and precision, wherever possible, get my vote - with an eye to the future.

Jarfi

Quote by sophiecentaur

Heat loss is quite complicated.
It seems to me that you are assuming that the heat is conducted in the form of 'vibrations'. That's the way they tell you about conduction in solids at school. However, in metals (amongst the most common solids we meet), the energy is transferred in the same way as electric current. The (outer) electrons are extremely mobile and move at a very high average velocity. So they travel freely inside the metal and carry excess Kinetic Energy about very fast through the metal. Both electrical and thermal conductivity are high.
The sensation of 'cold' when touching a cold metal is largely due to the fact that heat is transferred very fast and keeps the temperature of the surface that you are touching, low. Your hand just keeps losing heat. Touch a cold plastic object and its surface very soon starts to get to the same temperature as your hand because the conductivity is so low.

Of course, Specific Heat also counts and the overall cooling effect will depend upon both factors. The SH of water, for instance, is extremely high (much higher than metals) and water is an excellent coolant but, unless you stir it round (convection) it will not transfer the heat away as fast (wet suits work this way).

Wow... i did not know that electrons had a role invtransferring hear, so that would mean good electrical conductors are often good heat conducuctors. This has to relate with superconductors at low temperature somehow...

And to the precicion thing, i thunk we need both metaphors, "cute" descriptions And maths and other robotic things. Computers calculate better than any of us, insight matters

sophiecentaur

Quote by Jarfi

Wow... i did not know that electrons had a role in transferring heat, so that would mean good electrical conductors are often good heat conducuctors. This has to relate with superconductors at low temperature somehow...

This applies to metals. The best electrical conductors are metals and they are also good thermal conductors. Silver is at the top, I seem to remember.
Diamond is an exception to this rule because it is a good thermal conductor but a good electrical insulator - with an entirely different mode of thermal conduction. It would be a good candidate as a substrate for mounting integrated circuits.

Jarfi

Quote by sophiecentaur

This applies to metals. The best electrical conductors are metals and they are also good thermal conductors. Silver is at the top, I seem to remember.
Diamond is an exception to this rule because it is a good thermal conductor but a good electrical insulator - with an entirely different mode of thermal conduction. It would be a good candidate as a substrate for mounting integrated circuits.

Yes, thermal conductivity must be a combination of:

electrical conductivity whereas the electrons transport kinetic energy and,

Structural features, maybe distance between atoms, how rigid they are and how easily kinetic energy travels from one atom to the other. Maybe the diamond is good because the carbon atoms are all lined up next to each other, and held very rigidly so the atoms would hit each other often if they moved around.. since they are close together or/and electrically connected.

maybe some other things are included, like infrared radiation... this must be a field one could specialize in.

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sophiecentaur Recognitions: Gold Member Science Advisor	I don't teach any more but I see you are getting my point. I regard this forum in much the same way as I saw School. Rigour and precision, wherever possible, get my vote - with an eye to the future.