# How fast does fire travel?

Discussion in 'Physics & Math' started by Stryder, Sep 26, 2002.

1. ### StryderKeeper of "good" ideas.Valued Senior Member

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I awoke this morning to a question that foxed me, although I could answer certain points of it.

I can understand that fire moves at a very fast rate when consume flamable gases from the fact that it creates a noise that would be similar to an aircraft braking the sound barrier.

So it must travel faster than sound, if only with gas.

We know that fire emmits heat and light, which can cause nearby solids to be exposed to radiation. This how ever doesn't mean that it spreads the speed of light (or greater).

I suppose the only real way of answering it's speed would be to take into consideration what is being burnt and thermodynamics.

So does anybody actually have a clue how fast it travels?

3. ### Avatarsmoking revolverValued Senior Member

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I duno- it matters what you burn- the properties of that material..

suggestion- try an experiment- take a long plank of wood, spill it with petrolium and light it. record the time

aaa- hi btw, haven't talked to you some time

5. ### Thor"Pfft, Rebel scum!"Valued Senior Member

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That really is a noodle scratcher. I'll ask my buddy who does physics to ask his lecturer for you.

Thats it, thats another sleepless night of me wandering how fast fire is. Thanks

7. ### FrencheneeszAmazing MemberRegistered Senior Member

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Well, sorry, but it seems to me like its kinda a stupid question, no offence.

Fire doesn't emit light and heat. Fire IS light and heat. If you see a flame, something doesn't neccesarily have to be burning, for example, melted iron gives off a flame, seen as the yellow glow around it...

Flame will "move" as fast as the heat (that creates the light) is transferred. Different things will burn faster, which sometimes means a faster "moving" flame, but if you only have a speck of something and burn all of it at relatively the same time, it doesn't "move".

What heat is, is the electron speed of the atoms. The electrons bump into other atom's electrons, transmitting the heat, so the flame cannot move faster than the electrons.

8. ### On Radioactive Waveslost in the continuumRegistered Senior Member

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"What heat is, is the electron speed of the atoms"

wrong!!! heat is defined as the RANDOMLY oriented kinetic energy.

"melted iron gives off a flame, seen as the yellow around it"

thats radiation, not a flame. if there is a flame, it is because the iron reacted with oxygen. i can say this from a couple years of experience at cutting steel with oxygen.

i was watching a show on fireworks back in july, and they talked about some interesting high speed fuses. the fuse was a hollow tube, which burned at several hundread feet per second, with the aid of the expanding gases traveling down the tube.

9. ### FrencheneeszAmazing MemberRegistered Senior Member

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'wrong!!! heat is defined as the RANDOMLY oriented kinetic energy. "

Im sorry, but you are WRONG!!!! Maybe your definition of heat is different than mine, but the heat that we feel through our nervous system is created by the speed of electrons in the atoms of our nerve cells.

Electrons go faster, enlarging the electron shell, and when the electrons bump into other atoms' electrons, the atoms get knocked around every which way. It is "random" in the sence that it would be extremely hard to calculate the positions of everything and noone cares enough to do it. If we had a REALLy nice super computer we could do it.

If the car seat in your car gets hot, the atoms are not flying about, but are shaking in place which is why the seat doesn't just melt to the floor. The shaking is created by the fast speed and crashings of the electrons.

Random kinetic energy is a crappy definition to say the least.

Again it depends on your definition of "flame". My definition is a spot of light created by heat. In this way the radiation is the flame. Oxygen recations are not the only things that create a flame.

"with the aid of the expanding gases traveling down the tube."

The "speed" of a flame depends entirely on the rate of the reaction and the length of the reactant area. Thus in a long fuse with a high reaction rate, the flame may well go at high speeds, but no faster than an electron...

10. ### StryderKeeper of "good" ideas.Valued Senior Member

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Actually your both right, and still slightly out with how HEAT travels.

Heat doesn't travel through free floating electrons, that's electricity, heat travels through radiation that causes the electrons to resonate creating a kind of radioactive decay.

(namely the atom suddenly reaches it's radioactive lifeexpectancy as an atom)

This resonance and disturbance then causes the atom to release the energy that holds it's bonds, thus the destruction of the material and the continued chain-reaction of radiation.

[I couldn't of realised this straight away without you guys help

]

As for flames, it's thermodynamics, matricing of radiation from multiple locations merging and reacting with themselves and any free floating particles.

From this it can be worked out that fire has the radiation (Speed of light) which takes time to cause a radioactive decay (which would be dependant on how many electrons an atom has, how many free places in it's shell and how many other atoms are connected to it as a molecule), so fire travels as fast as the radioactive decay of the atoms it's consuming.

11. ### On Radioactive Waveslost in the continuumRegistered Senior Member

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"heat that we feel through our nervous system is created by the speed of electrons in the atoms of our nerve cells. "

i thought we were talking about fire? now you turn this into biology? are you talking about the potassium channels transmitting sensation? because now your talking about your body, and the question was about fire.... so unless you have a fire inside your body.... then the definition of heat you use should be pertaining to fire.

12. ### On Radioactive Waveslost in the continuumRegistered Senior Member

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Frencheneesz

"heat that we feel through our nervous system is created by the speed of electrons in the atoms of our nerve cells. "

are you saying the faster the electrons go, the hotter it feels? i think the electrons would always travel at about the same speed.

did you mean to say -- "heat that we feel through our nervous system is PROPAGATED AT the speed of electrons in the atoms of our nerve cells. " ?

if the speed creates the heat, then that means the speed is variable. i think you spoke too hastily.

13. ### FrencheneeszAmazing MemberRegistered Senior Member

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"i thought we were talking about fire? now you turn this into biology?"

I could have also said, the heat that is regestered in a thermometer. I was attempting to define what I thought was heat, just to be very precise about what "heat" was when i talked about it. Many arguements arise because the two sides have different definitions of the same word.

"are you saying the faster the electrons go, the hotter it feels?"

Exactly.

"i think the electrons would always travel at about the same speed."

Why would you think that? (serious question).

"did you mean to say -- "blah blah blah""

No I didn't, i said what i mean.

"if the speed creates the heat, then that means the speed is variable."

Yes, I mean to say the speed of electrons is variable. I think i explained it quite well in my previous post.

Is there any evidence that this is not so? If you have any I would LOVE to hear it (it would expand my understanding).

The variable speed of electrons allows for many properties of atoms: heat, the reason why hot air expands (because the orbits expand as the electrons go faster), the reason brownian motion happens (the "random" movement of particles), it allows for the reason there is a difference between solids and liquids, Gases and plasma. It is an improtant property of matter that is never fully described in school.

14. ### On Radioactive Waveslost in the continuumRegistered Senior Member

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the average speed of an electron in your potassium/sodium channel will always be the same. this is a chemical reaction.

you said that the speed of the electron is what describes the intensity of the heat. however, ir your body temperature is constant, wether you touch somthing cold or hot, your K/Na channels will still transmit the information at the same speed, therefore the intensity of the heat your body perceives is not governed by the speed of which the electrons travel through your potassium soduim channels.
if you know about temperture, you will know that an atom is not vibrating at absolute zero .when it heats up, it vibrates, or moves in place, which basicly ends up making it take up more space because it is moving in place ( you can disregaurd velocity).

the heat that is registered in a thermometer esentially measures the radius of the atom. at absolute zero, the atom is at its smallest size. when it increases its heat, it takes up more space (hence MOST things expandand when they get hotter) because the electrons vibrate farther away from the nucleus(point we are calling the center) of the atom.

now consider burning yourself with a peice of molten steel versus a flame that is cooler. how do electrons travel faster through your body depending on the intensity of wha is burning you? i think they dont. the object burning you would have to actually change your body temperature to change the reaction rate of the chemical reaction your brain senses. there must be variation of the intensity of the signal sent, not a constant signal sent sent at a variable speed ( i.e. if you touched the sun it would be so hot it burned before you touched it because the electrons traveled at such trememdous speed).

and when something is hotter, if you consider the electrons moving faster, it is only a product of the vibration, they still go about their orbitals at the same speed.

and please go by a scientific defintion, not your own. This is sciforums

15. ### On Radioactive Waveslost in the continuumRegistered Senior Member

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Stryderunknown

Stryderunknown

heat travels in three ways- conduction, convection, and radiation

16. ### FrencheneeszAmazing MemberRegistered Senior Member

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"the average speed of an electron in your potassium/sodium channel will always be the same. this is a chemical reaction. "

Doesn't it make sense that the faster the electrons go, the faster the reaction will go, by my definition, the more heat the faster the reaction, it works with the facts.

"your body temperature is constant, wether you touch somthing cold or hot"

The temperature in your finger would not be constant if you touch something hot or cold, I think you can agree.

"your K/Na channels will still transmit the information at the same speed"

I don't know what K/Na channels are, so what are they?

"is not governed by the speed of which the electrons travel through your potassium soduim channels."

When I said the speed of electrons, i meant the speed they are going in orbit around an atom. Electricity has similar effects, but is different because it is formed by the more or less straight movement of the electrons. The electrons in electricity heat up the wire by pushing the electrons in the atoms that make up the wire.

"if you know about temperture, you will know that an atom is not vibrating at absolute zero "

Im sorry, if you know about temperature, you would know that an atom does vibrate at what they call absolute zero. Now, by my definition of heat, absolute zero would be where the electrons dive into the atom's protons, creating a neutron ball which would not vibrate, but this is assuming that protons and electrons have substance other than their electromagnetic fields.

I would say that at absolute zero they do not vibrate, but science says otherwise.

"because the electrons vibrate farther away from the nucleus"

electrons do not vibrate, they have an orbit around a nucleus. The electromagnetic radiation from an atom is the effect that in the two dimentional scale the atom is moving back and forth along its orbit. An electron has an orbit much like the planets, except it is much more complicated with these electrons repel eachother, creating havoc to measure the position, speed, or direction of these infintesimally small objects. Thus some scientists like to say that it is impossible just because they cant do it, thus the uncertainty princible.

how do electrons travel faster through your body depending on the intensity of wha is burning you?

Again I did not mean electricity, If you had read my post, you would have found I explained quite well the process of heat. It said nothing about linear motion of electrons, and continually referenced the ORBITS of them. The electrons move faster, therefore increasing their orbit radius and also increasing the amount which it whacks other atoms away from it. The faster electron speed has many effects other than just heat.

Ya I think you did, um, but i don't remeber talking about how fast electrons travel, oh well.

If you don't think electron orbit speed is heat, then what is heat. You can not just talk about this arbitrary concept of heat. I think you refered to it as the random kinetic motion of atoms.

If that is your concept of heat, then tell me why when you shake a box of air, the difusion rate increases, but the heat only increases in such a small amount that it is unrecordable.

To create the same diffusion rate of the box of air, you would have to heat the box to hotter than the temperature it would be to shake it.

Stryderunknown:

Ya On radiation waves is right that heat travels in more than one way. Radiation makes up very little of the transmittion of heat, unless you take into acount that the electromagnetic field of the electrons is radiation, which most people don't recognize.

Most heat is transmitted by the electrons bumping into the electrons of other atoms.

One more thing, what is technically wrong with saying heat is electron speed. Would you care to give me a question about heat that i can't answer using my rendition and you can?

How would you say evaporation cooled things in your way?

17. ### On Radioactive Waveslost in the continuumRegistered Senior Member

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K is the symbol for potassium, Na is Sodium. there is a balance of their ions in your nerves and the two elements are used to transmit sensation.

yes, your finger would change temperature, but that would be a small part of the journey. the rest of the way, your body would probably still be 98 F.

okay, i guess the atoms would vibrate to the frequency acording to th deBroglie wavelength equation?

evaporation cools things by consuming the energy in the phase change.

in chemistry, elemnts can be written in subscript to show the phase (gas, liquid, solid, aqueas). a single water molecule at the same temperature has different amounts of energy depending on its phase. got to go.........

18. ### On Radioactive Waveslost in the continuumRegistered Senior Member

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i was not aware/ never thought of/ cant remember anything about that diffusion rate with shaking, but i would say that the reason it increases is beacause the air molecules are moving randomly, but they are not moving in unison. the ramdomly oriented energy of heat is moving in sync( i think) where as the moving air is not. i dont know if i explained this well, but here is an analogy.

imagine the box with a storm inside, instead of just air. when you shake the box, the temperature dosn't increase, but the wind storm will turn into a hurricane, its moving around faster (but still going in a circle , such that the net movement is zero.)

also think of this, that pressure is inverly proportional to heat by the equation pv=nrt, so the temperature exerts an outward pressure, where as the pressure is the inward pressure on an object and is the sum of all the outward pressure

19. ### StryderKeeper of "good" ideas.Valued Senior Member

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On Radioactive Waves got me in their sights and fired this volly:

"heat travels in three ways- conduction, convection, and radiation"

I previously mentioned "heat travels through radiation that causes the electrons to resonate creating a kind of radioactive decay"

Your right that I didn't point that the radiation conducts the heat through the convection of resonance. Just think of how a microwave oven works, although there is a point that a microwave oven doesn't burst what ever it is your cooking into flames, which means that there is something missing that would fit into what you mentioned.

Frencheneesz lobbed this passing statement:

"Radiation makes up very little of the transmittion of heat, unless you take into acount that the electromagnetic field of the electrons is radiation, which most people don't recognize.

Most heat is transmitted by the electrons bumping into the electrons of other atoms.
"

When you start looking at the EM field or (PSI waveformations as some know it) you start bringing the original topic of the speed of fire travelling into thermodynamics, and thats probably where it needs to go.

I'll continue to disagree that the bumping of electrons is the only reason for heat exchange though, as I would say it's still more likely to do with the resonance of the particles. Although I'm not ruling out that the collision of particles causes a release of energy.

(BTW, sorry for the odd entrance statements, I've got to stop hanging in newsgroups)

20. ### chrootCrackpot killerRegistered Senior Member

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Temperature is defined as the average kinetic energy of a particle in a substance. <K.E.> = 3/2*(kT) where k is Boltzmann's constant. This is a precise definition.

Internal energy is defined as the sum of the kinetic and potential energy of particles in the substance. This is a precise definition.

None of this has ANYTHING to do with electrons, so long as the substance is cool enough to remain unionized. The electrons don't move faster, nor does the atomic radius increase. That's all total hogwash.

The reason shaking a box of air doesn't result in a measurable temperature increase is because the atoms in normal air are already moving at very high velocities (solve 0.5mv^2 = 1.5kT if you don't believe me) and the extra velocity imparted on some of the particles by the shaking walls, moving at a few cm/s in your hands, is negligible.

"Thus some scientists like to say that it is impossible just because they cant do it, thus the uncertainty princible."

Sorry Frencheezy, you're wrong yet again.

- Warren

Last edited: Oct 2, 2002
21. ### odinRegistered Senior Member

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1,098
Very quickly when the material is explosive :bugeye:

22. ### FrencheneeszAmazing MemberRegistered Senior Member

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"the rest of the way, your body would probably still be 98 F. "

Yes, true I was not talking about electricity, which is how the heat is registered in the brain. Electricity can create heat (and does), but has different effects since it has an average linear motion.

"evaporation cools things by consuming the energy in the phase change."

How? I would explain yet again how I would say it happens, but Id rather my response be short.

"the ramdomly oriented energy of heat is moving in sync( i think) "

Nice rhyme, but if the particles "randomly" moved in unison, then it would be kinetic energy. Ill also point out that each individual particle in any material has a different temperature than the whole, only the average temperature can be accurately measured with today's equipment.

Chroot:

"as I would say it's still more likely to do with the resonance of the particles"

The resonance of the particle relate directly to the electrons. As the electrons spin around, they create a wave formation that can be said to be a "resonance". Each atom and molecule has a different electron configuration, thus a different "resonance".

"None of this has ANYTHING to do with electrons"

Im glad you think so, but don't you think that the electrons going at very high speeds as they do would bump into other atoms? Every property of an atom is sumed up in its electron shell's structure. The atoms outside a particular atom have no way of "feeling" the cells inner nucleus.

"(BTW, sorry for the odd entrance statements)"

I forgive you. If you don't make sense you can always blame the news.

"Temperature is defined as the average kinetic energy of a particle in a substance. "

There are many definitions of heat, my man. The average kinetic energy of a particle is the direction it is moving. As I said, the kinetic energy of a particle is related to the electrons motion, slamming into other atoms.

Can you give me a question that might prove my theory wrong?

"The electrons don't move faster, nor does the atomic radius increase"

Oh contrair (if i was french Id spell that right). I think you would be strongly opposed if you said atomic radius did not increase with temperature....

"The reason shaking a box of air doesn't result in a measurable temperature increase is because the atoms in normal air are already moving at very high velocities "

Interesting point, but damnit man, why do you have to make me think!? Im already in school. My actual point is that it takes much more heat to generate the rate of diffusion similar to shaking it....

"Sorry Frencheezy, you're wrong yet again."

Hey, the uncertainty princible has not been disproven, but neither has my theory. Go at it.

23. ### On Radioactive Waveslost in the continuumRegistered Senior Member

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okay, when i said "essentially increases the atomic radius" i said that to illustrate my point that the atom takes up more space. if you look at a good periodic table (i think sgt. welsch has it) it will the you the atomic radius of every element. the atomic radius grows larger with the increasing number of valence electrons, but once the orbital is completly filled the atomic radius becomes dramaticly smaller (compare flurine to neon)

some one correct me if i'm wrong, but heat it not the same thing as temperature

Frencheneesz

"Can you give me a question that might prove my theory wrong? "

okay, how about one atom in space, not remotely close enough to any other matter to bump into? one atom could absorb radiation, become excited and "hot" but not be able to cool off through conduction or convection. it would have to radiate the energy away, or touch anti matter or yada yada yada

the electron orbitals only increase in size when they increase specific energy levels, which emit signiture amounts of energy, which is how we are able to determine the composition of stars so far away (spectroscopy)