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Open Letter to Dave Thomas
- Thread starter cmatrix
- Start date
ergo
Illuminator
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So would you, so stop saying it is.
http://zonalandeducation.com/mstm/p...gy/heatAndTemperature/heatAndTemperature.html
http://zonalandeducation.com/mstm/p...gy/heatAndTemperature/heatAndTemperature.html
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W.D.Clinger
Philosopher
Sorry, but you have demonstrated once again that the problem is with you. The highlighted assertion is laughably incorrect.
Anyone can demonstrate your error by propping up a table leg so the table top is almost but not quite level, and by dropping a marble onto the table's top. From the time the marble leaves your hand to the time it hits the table, the marble is in free fall, but it is converting only some of its available gravitational potential energy to kinetic energy. It retains the rest of its available GPE, converting that remaining GPE to kinetic energy only as it rolls off the slanted table top and falls the rest of the way to the floor.
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ergo
Illuminator
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Please show exactly where you think I said it.
Newtons Bit
Penultimate Amazing
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I don't think that's what he's saying.
excaza
Illuminator
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Please show exactly where anyone said heat is temperature.
excaza
Illuminator
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You keep quoting NB saying "temperature is kinetic energy" and implying that he is saying "temperature is heat"
They do not mean the same thing.
W.D.Clinger
Philosopher
What do you think cmatrix is saying?
excaza
Illuminator
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It was posted a few pages ago.
ergo
Illuminator
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excaza, Newton's bit equated kinetic energy of molecules with temperature. He said they were the same thing. Temperature is not an energy. Heat is.
Heat is the kinetic energy of molecules. What else do you think it is?
triforcharity
Banned
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Of what?
excaza
Illuminator
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- Nov 19, 2007
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No.
W.D.Clinger
Philosopher
Both excaza and Newton's Bit have gotten a bit sloppy. When they said temperature is the kinetic energy of molecules (Newton's Bit) or just kinetic energy (excaza), they were omitting the words "average" and "per molecule". Both excaza and Newton's Bit are well aware that temperature is not heat, and have been trying to explain that to you.
You still don't get it, even after you have cited a web site that plainly says
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Oh, for the love of the FSM. I can't watch this any more.
There's three topics "under discussion" here, and by that I mean "misunderstood by a Truther." They are, respectively, heat, temperature, and measurement of temperature.
Heat is energy. Period. It has units of energy, viz. Joules, or is also expressed in more familiar units like Calories or BTUs (British Thermal Units). Heat is also sometimes called thermal energy to clarify that it is indeed energy.
Temperature is not energy. Temperature is an intrinsic property of a material. Every material has a temperature. Adding heat energy to an object increases its temperature, and under the right conditions heat energy can be removed from an object, decreasing its temperature. Temperature is measured in degrees, with Kelvins being the most useful from a scientific standpoint. One Kelvin (not "one degree Kelvin," it's just said "one Kelvin") is the same as one degree Celsius, the only difference is that 0 K is "absolute zero," or the coldest that any object can possibly be, whereas 0oC is referenced to the freezing point of water.
Then there is measuring temperature. Why do we measure temperature, and not thermal energy? The answer is simple -- until very recently, it was easier to measure temperature than to measure thermal energy content. The way we usually measure thermal energy is to take advantage of the concept of thermal equilibrium, which states that if two objects are in contact, heat will flow from the one with the higher temperature to the lower one.
We exploit this property as follows: We take an object with known properties, and we put it in contact with the object we wish to measure, until the two are in thermal equilibrium. It works better if our known object (our "thermometer") is small, so it doesn't take very much heat exchange for it and what we're measuring to reach equilibrium.
OK, so we've waited until our thermometer has either heated up or cooled down until it's in equilibrium with the mystery object. Now what? Well, temperature is, again, an intrinsic property. This property also affects other properties of the material -- its density, its flexibility, its volume, and so on. So if we measure our thermometer at known reference temperatures, we can determine its temperature (and by inference the temperature of what we're measuring) by measuring this other quantity. In the case of a mercury thermometer, we are measuring the volumetric change of the mercury column at different temperatures. In a needle-type thermometer, we are measuring the strain introduced in a bimetallic strip, the temperature causing it to coil or uncoil.
Why don't we measure heat directly? It's actually rather simple. Energy, as you should know, is neither created nor destroyed, but it can change form. Making it change form, however, is often quite difficult. We could measure heat by slicing off a piece of the material, sucking heat out of it until we reached absolute zero, and count it as we did so -- but this is extremely hard and expensive to do. Likewise, getting energy into the form of heat is not always easy either. In the laboratory, Lord Kelvin devised an apparatus where mechanical energy (either a turned crank or weights on pulleys) was converted into thermal energy by driving little paddles that turned in a viscous, well-insulated medium, dissipating the mechanical energy through turbulence. The brakes on your car are another method, using friction to convert kinetic energy into thermal energy (a whole lot of it). But turning that energy back into kinetic energy, or any other form, is tough. If it wasn't, many fewer of us would be overweight!
So how is heat actually manifest in an object? Heat is, at the very lowest level -- the atomic level -- a kinetic phenomenon. Within a crystal lattice heat is represented as phonons, or little energy packets that each correspond to a vibration propagating through the lattice. The word "phonon" is similar to "photon" for a good reason. But thermal energy is very different than kinetic energy or electromagnetic energy. The principal reason is that it is random. If a block of steel has some kinetic energy, that means the entire object has a constant relative velocity in some direction. In thermal energy, all the little atoms are moving, yes, but not in the same direction at all.
This totally random motion is called Brownian Motion. And because it is random, it is very difficult to get that energy back. There is no "one way filter" or anything we can apply to make them move in a certain direction (see Maxwell's Demon). This fact lies at the heart of the Second Law of Thermodynamics, which among other things states that it is not just thermal energy, it is also randomness (entropy) that defines an object's temperature, and that this randomness can only be removed at a cost somewhere else.
This randomness also describes why materials weaken as they increase in temperature. After the phonon energy rises past a certain level, the individual atoms in an object begin to displace an amount sufficiently large to strain or even break their intermolecular bonds. When enough of these bonds are broken (on average) at any given moment, the material will begin behaving more like a viscous liquid than a solid. This is the regime in which things like steel will "creep" under load -- they're not yet liquid, but over long periods of time, they will flow. What "long" means depends on the temperature and the load. Could be thousands of years, could be minutes. NIST spends a great deal of time describing the impact of creep in the structural collapses.
So now that we understand what heat and what temperature are, we next look at the relationship between them. Some materials require much more heat than others to reach a given temperature. This is a factor of many, many things, including the strength of molecular bonds, their type, the mass of individual molecules, the shape of the crystal lattice (if any), and so on. At the macroscale where we all live, we simply measure a constant called the specific heat of that material, i.e. how much energy does it take to raise the temperature of a unit mass by one Kelvin. In the laboratory, we take its temperature, apply a known amount of energy -- say a calibrated flame for a carefully monitored length of time, or one of Lord Kelvin's eggbeater energy converters if we want to be extremely careful -- and then measure the temperature afterward.
The specific heat of materials varies an enormous amount. Metals tend to have high specific heats, which is why they often feel "cold" to the touch -- they're not any colder than the rest of the environment, but they don't reach thermal equilibrium with your hand until more heat is transferred to them. Other materials can have extremely low specific heats. Here's a famous picture you've probably seen before:
This object is a piece of tile used in the Space Shuttle. The engineer heated it up by holding a blowtorch to it. The tile is so hot that it is illuminating the picture -- but you can still hold it. That's because its specific heat is so low that, despite its high temperature, it contains very little thermal energy, not enough to burn your finger.
During reentry, the Shuttle tiles reach thermal equilibrium with the plasma field outside, at very high temperature. Once they're at equilibrium, there is no additional heat transferred to the tile from the plasma. On the inside, the tiles are cooled by layers of insulation between the tiles and the structure of the Shuttle, and those never reach dangerous temperatures because the amount of heat isn't high enough to reach them.
The important lesson, however, is that heat and temperature are not the same. In a fire, both quantities are important -- the temperature of the plume determines the rate at which heat is transferred to structural elements, and the heat content of combustible materials puts a limit on the amount of heat energy available.
In the case of a structure fire, and the question of one causing damage to steel structural members, it is important to note that both temperature and heat content are very, very high. NIST, in NCSTAR1-5E, conducted controlled tests of workstation fires to measure both the temperature curve and the total heat content of those workstations, under varying conditions having to do with ventilation, ignition, whether intact or knocked down, etc. NIST found that gas temperatures over 1000oC were commonplace, and temperatures over 1400oC happened at least once. Yes, you read that right -- 1400oC. That's above the melting point of some steels, in an "ordinary" office fire. NIST was unable to find the absolute maximum as their recording equipment was destroyed at that temperature.
The amount of heat in an "ordinary" fire is also extremely high. NIST expressed this not in terms of energy, i.e., Joules, but instead in terms of power, or the amount of thermal energy converted from chemical energy (i.e. burning) per second. One Joule per second is one Watt (W). NIST determined that the power of an individual, average office workstation is about 8 to 9 megawatts, again depending on conditions of the individual test.
For comparison, the ABL flying laser, designed to shoot down missiles, operates at one megawatt.
It's not exactly a straight comparison, but the lesson is clear: "Ordinary" fires are no joke.
To conclude:
That should about do it. Thank you for your attention.
There's three topics "under discussion" here, and by that I mean "misunderstood by a Truther." They are, respectively, heat, temperature, and measurement of temperature.
Heat is energy. Period. It has units of energy, viz. Joules, or is also expressed in more familiar units like Calories or BTUs (British Thermal Units). Heat is also sometimes called thermal energy to clarify that it is indeed energy.
Temperature is not energy. Temperature is an intrinsic property of a material. Every material has a temperature. Adding heat energy to an object increases its temperature, and under the right conditions heat energy can be removed from an object, decreasing its temperature. Temperature is measured in degrees, with Kelvins being the most useful from a scientific standpoint. One Kelvin (not "one degree Kelvin," it's just said "one Kelvin") is the same as one degree Celsius, the only difference is that 0 K is "absolute zero," or the coldest that any object can possibly be, whereas 0oC is referenced to the freezing point of water.
Then there is measuring temperature. Why do we measure temperature, and not thermal energy? The answer is simple -- until very recently, it was easier to measure temperature than to measure thermal energy content. The way we usually measure thermal energy is to take advantage of the concept of thermal equilibrium, which states that if two objects are in contact, heat will flow from the one with the higher temperature to the lower one.
We exploit this property as follows: We take an object with known properties, and we put it in contact with the object we wish to measure, until the two are in thermal equilibrium. It works better if our known object (our "thermometer") is small, so it doesn't take very much heat exchange for it and what we're measuring to reach equilibrium.
OK, so we've waited until our thermometer has either heated up or cooled down until it's in equilibrium with the mystery object. Now what? Well, temperature is, again, an intrinsic property. This property also affects other properties of the material -- its density, its flexibility, its volume, and so on. So if we measure our thermometer at known reference temperatures, we can determine its temperature (and by inference the temperature of what we're measuring) by measuring this other quantity. In the case of a mercury thermometer, we are measuring the volumetric change of the mercury column at different temperatures. In a needle-type thermometer, we are measuring the strain introduced in a bimetallic strip, the temperature causing it to coil or uncoil.
Why don't we measure heat directly? It's actually rather simple. Energy, as you should know, is neither created nor destroyed, but it can change form. Making it change form, however, is often quite difficult. We could measure heat by slicing off a piece of the material, sucking heat out of it until we reached absolute zero, and count it as we did so -- but this is extremely hard and expensive to do. Likewise, getting energy into the form of heat is not always easy either. In the laboratory, Lord Kelvin devised an apparatus where mechanical energy (either a turned crank or weights on pulleys) was converted into thermal energy by driving little paddles that turned in a viscous, well-insulated medium, dissipating the mechanical energy through turbulence. The brakes on your car are another method, using friction to convert kinetic energy into thermal energy (a whole lot of it). But turning that energy back into kinetic energy, or any other form, is tough. If it wasn't, many fewer of us would be overweight!
So how is heat actually manifest in an object? Heat is, at the very lowest level -- the atomic level -- a kinetic phenomenon. Within a crystal lattice heat is represented as phonons, or little energy packets that each correspond to a vibration propagating through the lattice. The word "phonon" is similar to "photon" for a good reason. But thermal energy is very different than kinetic energy or electromagnetic energy. The principal reason is that it is random. If a block of steel has some kinetic energy, that means the entire object has a constant relative velocity in some direction. In thermal energy, all the little atoms are moving, yes, but not in the same direction at all.
This totally random motion is called Brownian Motion. And because it is random, it is very difficult to get that energy back. There is no "one way filter" or anything we can apply to make them move in a certain direction (see Maxwell's Demon). This fact lies at the heart of the Second Law of Thermodynamics, which among other things states that it is not just thermal energy, it is also randomness (entropy) that defines an object's temperature, and that this randomness can only be removed at a cost somewhere else.
This randomness also describes why materials weaken as they increase in temperature. After the phonon energy rises past a certain level, the individual atoms in an object begin to displace an amount sufficiently large to strain or even break their intermolecular bonds. When enough of these bonds are broken (on average) at any given moment, the material will begin behaving more like a viscous liquid than a solid. This is the regime in which things like steel will "creep" under load -- they're not yet liquid, but over long periods of time, they will flow. What "long" means depends on the temperature and the load. Could be thousands of years, could be minutes. NIST spends a great deal of time describing the impact of creep in the structural collapses.
So now that we understand what heat and what temperature are, we next look at the relationship between them. Some materials require much more heat than others to reach a given temperature. This is a factor of many, many things, including the strength of molecular bonds, their type, the mass of individual molecules, the shape of the crystal lattice (if any), and so on. At the macroscale where we all live, we simply measure a constant called the specific heat of that material, i.e. how much energy does it take to raise the temperature of a unit mass by one Kelvin. In the laboratory, we take its temperature, apply a known amount of energy -- say a calibrated flame for a carefully monitored length of time, or one of Lord Kelvin's eggbeater energy converters if we want to be extremely careful -- and then measure the temperature afterward.
The specific heat of materials varies an enormous amount. Metals tend to have high specific heats, which is why they often feel "cold" to the touch -- they're not any colder than the rest of the environment, but they don't reach thermal equilibrium with your hand until more heat is transferred to them. Other materials can have extremely low specific heats. Here's a famous picture you've probably seen before:
This object is a piece of tile used in the Space Shuttle. The engineer heated it up by holding a blowtorch to it. The tile is so hot that it is illuminating the picture -- but you can still hold it. That's because its specific heat is so low that, despite its high temperature, it contains very little thermal energy, not enough to burn your finger.
During reentry, the Shuttle tiles reach thermal equilibrium with the plasma field outside, at very high temperature. Once they're at equilibrium, there is no additional heat transferred to the tile from the plasma. On the inside, the tiles are cooled by layers of insulation between the tiles and the structure of the Shuttle, and those never reach dangerous temperatures because the amount of heat isn't high enough to reach them.
The important lesson, however, is that heat and temperature are not the same. In a fire, both quantities are important -- the temperature of the plume determines the rate at which heat is transferred to structural elements, and the heat content of combustible materials puts a limit on the amount of heat energy available.
In the case of a structure fire, and the question of one causing damage to steel structural members, it is important to note that both temperature and heat content are very, very high. NIST, in NCSTAR1-5E, conducted controlled tests of workstation fires to measure both the temperature curve and the total heat content of those workstations, under varying conditions having to do with ventilation, ignition, whether intact or knocked down, etc. NIST found that gas temperatures over 1000oC were commonplace, and temperatures over 1400oC happened at least once. Yes, you read that right -- 1400oC. That's above the melting point of some steels, in an "ordinary" office fire. NIST was unable to find the absolute maximum as their recording equipment was destroyed at that temperature.
The amount of heat in an "ordinary" fire is also extremely high. NIST expressed this not in terms of energy, i.e., Joules, but instead in terms of power, or the amount of thermal energy converted from chemical energy (i.e. burning) per second. One Joule per second is one Watt (W). NIST determined that the power of an individual, average office workstation is about 8 to 9 megawatts, again depending on conditions of the individual test.
For comparison, the ABL flying laser, designed to shoot down missiles, operates at one megawatt.
It's not exactly a straight comparison, but the lesson is clear: "Ordinary" fires are no joke.
To conclude:
- Heat and Temperature are different things. They are not directly comparable.
- Both heat and temperature are required to cause damage to structures.
- There is plenty of experimental evidence to show that normal furniture, paper, etc. throw off enough heat, and burn at high enough temperature, to threaten structures.
- Anyone unclear on the definitions of "heat" and "temperature" must remedy his educational shortcomings before any intelligent discussion of NIST's findings is possible.
That should about do it. Thank you for your attention.
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Incorrect.
One more time -- only one more time -- temperature is not a measurement of heat. It is an intrinsic property of the material. Temperature is related to heat, but it is not heat.
Temperature includes how heat affects the material. Some materials are more heat resistant than others. Guess how? Because their temperature goes up more slowly as heat is added, that's how.
It is not heat, it is temperature that causes steel to weaken thermally. Temperature is one of the effects of added heat. Weakening is an effect of the increased temperature, i.e. the random motion of individual atoms in the lattice. It's very simple to understand. Newtons Bit understands this, as dare I say does everyone posting except yourself. I believe you'll find a more humble and open attitude will serve you well in this situation.
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No. Temperature is not a measurement of kinetic energy. It's more complicated than that.
If you have two materials where the average random velocity of the particles, and the average mass of the particles, is the same, they do not necessarily have the same temperature. Diamond and graphite, for instance, same mass, same composition. Same temperature means different energies! This is due to density of available states in the crystal lattice -- something you'll just have to go to school to learn, there's no point to getting into it here.
The reason no one can explain it to you is because you are totally lost. Science has its own language, and it takes some time to learn. What you're doing is fumbling around with it, saying things that you think you understand, but you don't.
There's no shame in not understanding it. It takes years to learn these things, and some people find they have no aptitude for it in the first place. But you should be deeply ashamed for carrying on as though you do, and attacking those who tried to explain it to you. You're wrong, plain and simple, and you lack the ability to even understand how you're wrong.
None of this can be cured overnight. Go to school.