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>heat is caused by rapidly moving molecules
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You are currently reading a thread in /sci/ - Science & Math

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>heat is caused by rapidly moving molecules
>heat is caused by infrared light

Which is it? Are scientists lying to me?
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>>7762599
heat isn't caused by anything, it is literally energy
it's rate of transfer is related to the temperature
energy can be transmitted both via momentum transfer when particles collide and light absorption, not just IR light either
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>heat is the rapid movement of molecules
>heat is often transferred in the form of infrared light
There ya go.
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>>7762603
So heat is entropy in measurement?
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>>7762610
Am I being trolled right now?
No, heat isn't entropy. All of the things we mentioned so far are well defined concepts with formulas of their own.
For example
Q=m.c.dT, Q: heat & dT: change in temperature
Entropy has several versions that can be defined in various ways, check it out yourself
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>>7762610
entropy is the number of ways heat can be transferred in a system.
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>>7762610

http://www.chem.uwec.edu/Chem150_F10/elaborations/unit3/unit3-b-energy.html
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Heat is a meme and was just invented so people can say energy conservation is true, which clearly isn't.

>blah blah there is friction which converts kinetic energy to heat
Yeah nah, faggot. Your shitty theory is just wrong.
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>>7762599
phonons m8
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>>7762599
Also

>Heat is caused by infrared light
>But sunburns are caused by ultraviolet
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>>7762599
Heat produces infrared light, you chud
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>>7762681
>Heat is a meme and was just invented so people can say energy conservation is true, which clearly isn't.

8/10
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>>7762828
So atoms vibrating causes heat, which causes infrared light.

But atoms absorbing and emitting photons causes infrared light.

So which is it?
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>>7762831
It's energy being released and energy being captured.
A microphone and a set of speakers do the exact opposite thing ; however they both work on the same principle, only one releases a sonic wave and the other absorbs it.
I have no idea if my comparison makes any sense, I'm reasonably drunk rn
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>>7762599
Rapidly moving atoms generate a spectrum of electromagnetic radiation.

For objects that aren't colder than liquid nitrogen, or as hot as the Sun, most of that radiation is in the infrared region.

When atoms are hit by electromagnetic radiation, they move.
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>>7762831
>So atoms vibrating causes heat, which causes infrared light.
>But atoms absorbing and emitting photons causes infrared light

Both. Vibrating molecules can lose energy by emitting a photon. They can also gain energy and start vibrating by absorbing a photon. (Or by knocking into a higher-energy molecule)

The spectrum of emitted radiation is such that, at normal temperatures, most emitted radiation is infrared. Heat it up enough and the peak wavelength will edge into the visible; cool it down enough and most of the faint thermal radiation will be microwaves. Planck's law describes the spectrum.
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>>7762599
infrared light is caused by rapidly moving molecules

rapidly moving molecules are caused by infrared light
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>>7762599
Both or true, modulo the misuse of the world heat.
Most of heat transfer is done though conduction (agitated molecules agitate the nearby ones) and convection (cold molecules move to hot places because which have lower pressure)
Infrared heat transmission only becomes perceivable at high temperatures or in vacuum.
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>>7763529
*are
*word
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>>7762599
I thought heat was the degree of agitation of eletrons, therefore the degree if agitation of molecules. Am I wrong?
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>>7763536
Other way around: When the energetic molecules collide, this can bump their electrons around, which causes photons to be emitted when they relax.
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>>7762599
Is the idea that light could cause molecules to move really so hard to believe?
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>>7762681
>the universe is an open system
Whut
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>>7762681
Oh wait I get it now, this is just a highschool-tier faggot who hasn't taken thermodynamics yet.

Poor baby :^(
>>
Semi-related question: is heat counted as momentum when looking at the conservation of momentum and heat as a result of friction?
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>>7763883
Not usually, because the internal momentum of a hot object is equally distributed in all directions, so the net momentum is zero.
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>>7763980
It seems like momentum isn't conserved because momentum is lost when energy is transferred through heat. How does it not violate the conservation?
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>>7763998
I have no idea where you got that impression.

Momentum isn't like energy, where it's a number you add up; it's a vector, with both magnitude and direction.

If two objects have the same momentum in opposite directions, the net momentum is zero. It's totally OK to create arbitrary amounts of momentum as long as something else gets the same momentum in the opposite direction - still totals to zero, so conservation is maintained.
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how does this work then
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>>7762599
An Electromagnetic wave shakes a particle which releases smaller electromagnetic waves (photons). Photons are crazy little motherfuckers, and when they hit shit that shit gets all excited yo and get real hot dawg.
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>>7764252
Electromagnetic waves mane. Like one of those there microwaves
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>>7764252
Its based on quantum tunelling. The energy is tunelled through electrons excitement and reach you as a heat.
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>>7764232
Oh I see, thanks. I have no formal education
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>>7762599
Molecules absorb infrared radiation and convert that energy to higher translational energy states.

So infrared light "causes" in a roundabout way, but it is not the only cause. Really, it's just molecules absorbing infrared light and converting it into translational energy, which is heat.

This is analogous to molecules absorbing UV, visible and sometimes near infrared light and re-emitting that absorbed energy as a lower frequency of light.

This is also analogous to molecules that absorb microwave radiation and convert into higher rotational energy levels.

All matter will absorb energy in the form of light, and will usually re-emit some of that energy while transferring the absorbed light into another form of energy.

An interesting connection to make here is that absorption of energy to make heat and absorption of energy to make light are mathematically very similar. You could argue that the are identical except for the magnitude of energy involved in absorption. Neat!
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>>7762681
Heh

Needed that thanks
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>>7762599
It's this shit again
They always lied
>Chemistry
>Atoms look like what we see in Lewis structures
>Move up, no that's wrong, actually they have configurations in SPDF and electron in box. Aka Pauli Exclusion principle
>then more shit comes in after that
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Physicist here:

https://en.wikipedia.org/wiki/Black-body_radiation

Heat by definition is the energy (mechanical or electromagnetic radiation) that is being transferred from one system to another system.

In a solid the atoms can vibrate and transfer the kinetic force to the particle next to it. How do they transfer this vibration without touching the other atom? Electromagnetic forces between the electron cloud of each atom repel each other when they get to close effectively acting like a "collision" I hope this is a simple enough explanation of how heat transfers conductively and convectively. Conductive for solids and Convective for gases.

But to explain heat as Infrared we need quantum mechanics and Electricity and Magnetism. When 2 particles are about to collide they are moving relatively at a constant velocity. But when the electron clouds get closer they start to repel. This causes the electrons to DECELERATE. electromagnetic waves are created when electrons accelerate and decelerate. This can also be viewed as the atom's energy decreasing. Now if you have a whole bunch of these atoms and a whole bunch of theses random collisions then you will have a lot of radiation being emitted. But that isn't the end of it. The radiation at the inner regions of the solid will get reobsorbed by neighboring atoms and either cause them to move kinetically or re-emit the radiation again and again all in random direction at random energies. If the temperatures are high enough then the atoms or compounds don't undergo any chemical changes (react). This is pretty much black body radiation. It is only at the edges of the solid does the radiation finally escape. For most temperatures on earth this radiation peaks in the Infrared region of EM radiation.
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>>7765205
I'm pretty sure it's called bremsstrahlung

https://en.m.wikipedia.org/wiki/Bremsstrahlung
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>>7765993
That is high energy free electrons passing by the a nucleus. I'm talking about low energy bound electrons in an atom accelerating and decelerating (gaining or giving energy as radiation).
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>>7762599
/sci/ is fucking retarded

Heat is atoms vibrating and colliding. The hotter the faster they move around. Lots of things can cause heat, including but not limited to infrared light.
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OP is an idiot.
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>>7762607
/thread
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infrared light is caused by hot objects giving off blackbody radiation

3/10 I replied
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>>7766996
How's your high school chemistry class so far?
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>>7766996
>lots of things can cause heat, including but not limited to infrared light

where's your source on this? oh yeah you don't have one because this is wrong
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>>7762684
/thread
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>>7762599
>heat is caused by

Stop right there. Heat isn't 'caused' heat is a measurable quantity.

Kinetic energy, for example, isn't 'caused' by anything. It is a measurable quantity. It depends on a systems mass, and it's velocity.

For a closed system in which all work done BY the system is adiabatic a change in energy of the system is equal to:
Delta Energy = HEAT - WORK

Heat is literally some sort of 'energy' that can be 'transferred' from one body to another.

Heat isn't temperature. Heat is just 'energy.'
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>>7762599
Phlogiston creates heat, didn't you know?
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>>7764252
Hey! How exactly is a rainbow made? How exactly does a sun set? How exactly does a posi-trac rear-end on a Plymouth work? It just does.
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