What the guy meant was that a change of 1 degree Celsius is the same change in energy as a change of 1 degree Kelvin, not that 1K=1C. Ofcourse you are right about 0K=-273C.StBishop said:Not quite.mooncalf said:A degree celsius is equal to one kelvin or 1.8 degrees farenheit. I'm not sure how to meaningfully express what "amount of vibration" a degree celsius is, perhaps look into that yourself and get back to us with the answer?
The Celcius scale lines up with the Kelvin scale but 1C is equal to 274K.
Different perspective 0 degrees Kelvin = -273 Degrees Celcius.
Question: What the Hell IS temperature anyway?
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Maybe, but scientists have been trying to create a zero kelvin freezer for years. They've got within a fourteenth of a degree, but haven't gotten quite there. So, while that sounds right, it probably is more complicated.Trivun said:
Unfortunately it doesn't work that way. The bell jar itself contains molecules, and those molecules will vibrate, giving off heat. Absolute zero is the cessation of all movement from within an atom, which simply just won't happen. Even in a "total" vacuum there will be some stray atoms, of at the very least quarks which will still be moving. Absolute zero is only a theoretical state of matterTrivun said:
Your skin is (most of the time) warmer than the air around it. This mean thermal energy will flow from your skin to the air around you.wkrepelin said:
The bigger the difference in temperature, the faster the energy gets transferred.
Now, the air just touching your skin is already warmed up by your skin, so it slows down the transfer of heat.
This layer of air can be called a boundary layer. When there's a current of air though, that warmer layer of air is constantly blown away and replaced by colder, fresh air. Because it's colder, energy is transferred faster, you lose heat more easily in a cold wind. The reverse is also true (that's why there's an hot air current in an oven).
This is also why all the little hairs on your arms stand up when you're cold. They try to keep that warmer layer of air in place so you don't cool off that fast. Of course this hardly does anything, but it really helped our ancestors, who were much hairier and had to deal with cold temperatures.
Temperature is subjective, since people feel heat differently, due to many factors, like nerve cells effiency, body fat, and a range of other factors. Temperature is just the signals your nerve cells send to your brain, being either hot or cold.
Because you just tried to apply the nanoscopic world to the macroscopic. There is actually an area around your body where a lot of your radiated heat sits before heading off into the world. The wind displaces those pockets and diffusion/entropy takes place from there.wkrepelin said:
This is what temperature is temperature is the measure of the hotness or coldness of a body. While Heat is a form of kinetic energy also known as internal energy. It is the vibrations or movement of the molecules of a substance. This creates convection currents. It can also be transferred through radiation and conduction but that is a bit pointless here.
So temperature does not equal heat. Temperature is the measure of it with two main scales. Celsius and Kelvin and then there's Fahrenheit too but that is a woeful scale. Kelvin starts at -237.15 [sup]o[/sup]Celsius and a rise of 1K = 1[sup]o[/sup]C. The 0 of Kelvin is a point where all the molecules stop moving. So no vibration will occur in solids, and no convection in liquids and gases, etc. While Cesius denotesa the boiling points and freezing points of water. No one actually knows what Fahrenheit is supposed to be.
So temperature does not equal heat. Temperature is the measure of it with two main scales. Celsius and Kelvin and then there's Fahrenheit too but that is a woeful scale. Kelvin starts at -237.15 [sup]o[/sup]Celsius and a rise of 1K = 1[sup]o[/sup]C. The 0 of Kelvin is a point where all the molecules stop moving. So no vibration will occur in solids, and no convection in liquids and gases, etc. While Cesius denotesa the boiling points and freezing points of water. No one actually knows what Fahrenheit is supposed to be.
Heya, professional physicist here.
Temperature is not a measure of energy. The technical definition of temperature is the reciprocal of the instantaneous change of entropy in regard to energy of the object. I will try to explain what that actually means.
If you want an analogy, imagine you have a town full of people. These people have a fixed amount of money to pass between them. The townspeople's goal is to make everybody as happy as possible by passing out their money. People who have lots of money will give some money to people who don't have as much. People who don't want money will give their money to people who do.
In this analogy, each person is a particle, like a single molecule of water.
Energy is money. There is a fixed amount of it and the town as a whole will never gain or lose money, even as money is passed from person to person.
Entropy is happiness. A particle's entropy is an individual person's happiness. The second law of thermodynamics states that the entropy of a system always increases. So in this town, a person will always hand his money to a person who wants it more, until the whole town is as happy as possible.
Do you remember what a reciprocal is? The reciprocal of a number is one divided by the number. So the reciprocal of 2 is 1/2, the reciprocal of 3/2 is 2/3, etc. The higher a number is, the lower its reciprocal.
So what is temperature? Temperature is the reciprocal of the amount of happiness a person gains from receiving money. So a person who is poor and wants money has a very low temperature. Someone who is rich and doesn't want any money has a high temperature. (High happiness from gaining money = low temperature, and vice versa) In general, the higher the temperature of a particle, the more energy he releases. The higher the temperature of a person, the more money he gives away.
Let's go back to actual physics. Say you have a jug of water. Each particle of water has some amount of energy and some amount of entropy. In general, the more energy a particle has, the more entropy it has. (This is almost always true. We won't get into exceptions here.) A particle with a lot of energy will tend to give energy to a particle with a little energy. The jug of water will always gain more entropy over time. The temperature of each water particle is a measure of how generous that particle is with its energy. A particle with more energy has a higher temperature, but energy and temperature are not the same thing. Incidentally, since every water particle is the same, the jug of water's entropy will be maxed out when every particle has exactly the same amount of energy.
So how about the temperature of the jug of water as a whole? Well, now we have to add the outside air to the system. Water particles on the surface will give and receive energy from air particles that get close. In this case, the temperature of the jug of water is the water's willingness to give energy to the air. Over time, the jug of water will reach equilibrium when its temperature of the same as the air: when the water is equally willing to give energy to the air as the air is willing to give energy to the water.
I hope that helps. Sorry if that was kind of convoluted, please let me know if you have any questions.
Temperature is not a measure of energy. The technical definition of temperature is the reciprocal of the instantaneous change of entropy in regard to energy of the object. I will try to explain what that actually means.
If you want an analogy, imagine you have a town full of people. These people have a fixed amount of money to pass between them. The townspeople's goal is to make everybody as happy as possible by passing out their money. People who have lots of money will give some money to people who don't have as much. People who don't want money will give their money to people who do.
In this analogy, each person is a particle, like a single molecule of water.
Energy is money. There is a fixed amount of it and the town as a whole will never gain or lose money, even as money is passed from person to person.
Entropy is happiness. A particle's entropy is an individual person's happiness. The second law of thermodynamics states that the entropy of a system always increases. So in this town, a person will always hand his money to a person who wants it more, until the whole town is as happy as possible.
Do you remember what a reciprocal is? The reciprocal of a number is one divided by the number. So the reciprocal of 2 is 1/2, the reciprocal of 3/2 is 2/3, etc. The higher a number is, the lower its reciprocal.
So what is temperature? Temperature is the reciprocal of the amount of happiness a person gains from receiving money. So a person who is poor and wants money has a very low temperature. Someone who is rich and doesn't want any money has a high temperature. (High happiness from gaining money = low temperature, and vice versa) In general, the higher the temperature of a particle, the more energy he releases. The higher the temperature of a person, the more money he gives away.
Let's go back to actual physics. Say you have a jug of water. Each particle of water has some amount of energy and some amount of entropy. In general, the more energy a particle has, the more entropy it has. (This is almost always true. We won't get into exceptions here.) A particle with a lot of energy will tend to give energy to a particle with a little energy. The jug of water will always gain more entropy over time. The temperature of each water particle is a measure of how generous that particle is with its energy. A particle with more energy has a higher temperature, but energy and temperature are not the same thing. Incidentally, since every water particle is the same, the jug of water's entropy will be maxed out when every particle has exactly the same amount of energy.
So how about the temperature of the jug of water as a whole? Well, now we have to add the outside air to the system. Water particles on the surface will give and receive energy from air particles that get close. In this case, the temperature of the jug of water is the water's willingness to give energy to the air. Over time, the jug of water will reach equilibrium when its temperature of the same as the air: when the water is equally willing to give energy to the air as the air is willing to give energy to the water.
I hope that helps. Sorry if that was kind of convoluted, please let me know if you have any questions.
Heat is molecules moving relatively to each other - you can't as a body move as the molecules, it is as if you were trying to move the same speed as a football team, a bunch of people running with different speeds at different directions, you can either move as one of the "people" and that wouldn't affect anything, or you could move as the "peoples" average and that wouldn't affect anything either. Now if your body's molecules were to move at the average speed as the average speed of the molecules around your body then both you and your surroundings would have the same temperature.
As has already been stated, you can't really translate temperature into energy/vibration/something directly; you need to nail down a bunch of other factors before you can say something meaningful about the effect of temperature change.wkrepelin said:
Ahem. *Straightens lab coat, produces blackboard from thin air*
[EDIT: also see the post above, as a professional physicist Blalien is probably a lot less rusty on this stuff.]
Consider the law of ideal gases: PV = NkT, where P and V are the pressure and volume of the gas, N is the number of gas molecules, T is the temperature and k is Boltzmann's constant, ≈ 1.38*10^-23 J/K (J is for Joule, energy and K is for Kelvin, temperature)
This really only applies to ideal gases which are impossible in reality, won't get into why - suffice it to say that they behave in a much simpler manner than real gases. But, for the sake of argument, let's assume that we're dealing with an ideal gas, so we can use the equation.
If we keep the amount of gas (N) constant and change the temperature, the value of the right side changes - let's say we increase the temperature by 1°C (= 1 K), so the value NkT increases. The left side then needs to increase (or decrease as the case may be) to still fulfill the equality. If the volume is constant, the pressure must then increase (heat a gas tube, and the pressure inside will increase - until it go boom!); if the pressure is constant, the volume must increase (hot air in atmospheric pressure expands, which as you know is the how of balloons =)).
(And if neither are constant it turns into a little headache)
In summary, you need to keep everything except the temperature and *one* other factor at a set value, then you can correlate a change in that other factor, dependent on the temperature.
So there ya go ... if you think this sounds complicated, I can't recommend getting a physics textbook. They're generally worse
This has been today's installment of (Indirectly)AskAnEngineer, stay tuned for more SCIENCE!!!
You did a whole lot of right in that post there, but I do believe you have a mistake there - a single particle doesn't have temperature, temperature is an average of a certain quantity of particles. Temperature is relative to the surrounding particles, the temperature of a lone particle is as meaningless as a body's speed relative to nothing.blalien said:
Yeah that's right, my bad. My analogy is a bit off in that respect.xdgt said:
Here's how that bold statement should have gone:
Temperature is a person's relative generosity. A person's temperature is how willing he is to give away money compared to his neighbors' willingness to give him money. A person with temperature higher than the average will give away more money than he receives, and vice versa. A person with the same temperature as the average will still pass around money, but he always gives the same amount of money as he gets back.
That's something you make up in your head. Say you burn a bit of your arm. The receptors in that piece of skin will sense extreme heat. The nerves will pass that information to the unconscious part of your brain, which translates the message and sends it to the conscious part. That message is the "hot" feeling.zehydra said:
Is it?ColdStorage said:
I don't think I learnt that name for it in the lectures, but we didn't go into it very much.
