I think that to explain a complex concept it is useful to make a similitude with another system that the students can visualize easily in they experience.
In the case of heat and temperature, it is almost straightforward the similitude with bowls filled by water:
water volume > heat content
water height > temperature
This similitude can help to explain also the heat capacity: a cylindrical bowl with larger base reaches a lower height than a bowl with a smaller base.
But this similitude can explain also the dependence of the specific heat on the temperature: the bowl geometry determined by the section S as a function of the height h, S(h) correspond to dQ/dT.
Connecting the bowls can explain the equilibration of two bowls connected by a pipe in the bottom: what we have is that the heights reaches the same value and not the quantity of water.
Moreover, we can also explain the role of the formation energy, putting the base of two connected bowls at different height.
A question arises: there is a physical reason that makes hydrostatic (in gravity) and thermodynamics so similar? I think yes, because both systems represent a way of storing energy.
Heat is a one type of energy ,but Temperature is intensity of heat .Simply temperature express intensity of heat .
Dear Ahmed,
Temp. is the intensity of heat as Mr. Jagadeesh Senapathi said. It means Temp. is independent to amount of materials. 1 Kg Iron in 500C has equal temp with 1 g iron in this temp. but their heats are different for reaching to 500C for 1 Kg iron you should spend 1000 times heat than 1 g iron. Because Q=mC(T2-T1), it means heat (Q) has direct relation with mass (m).
Temperature is an intensive property of a thermodynamic system related to the average kinetic energy of its constitutive particles. It is defined through the Zero(th) Law of Thermodynamics (if systems A and B, two closed and rigid systems, are in equilibrium and systems B and C are in equilibrium, then systems A and C are in equilibrium. Being in equilibrium means that if they are put in contact by a non-adiabatic boundary, no changes are observed in either system and energy is not exchanged between them. Then, there is a universal property with an identical value for those systems in thermal equilibrium: temperature). Entropy and temperature are conjugate variables. Temperature is a state variable, and it is defined in a given state.
Heat is a form of energy that is transferred between systems or subsystems by virtue of temperature differences. If two systems have the same temperature, when they are in contact they do not exchange energy in the form of heat. If they have different temperatures, they exchange energy in the form of heat (energy is transferred from the one with higher temperature to the one with lower temperature, according to the Second Law of Thermodynamics). Heat is not a state variable, but a process variable; it is not defined for a state, but for a process.
Temperature, entropy and heat are related: dQ≤TdS, where the equal sign corresponds to reversible processes.
thank you very much dear Luisiana Cundin ·. . thanks a lot Jagadeesh Senapathi
. its a nice explanation Hamed Omid-thank you
Adrian Velazquez-Campoy
To explain this to a person without a technical background, say a 6-year old, I would start by explaining that all matter is built up from tiny tiny particles.
I would proceed by explaining that these particles are vibrating. The temperature is a way to tell how intensely they are vibrating. High temperature represents high intensity vibrations.
The particles may "collide" with each other, and then they affect each other such that the most vibrant particle gives some of its vibration to the less vibrant particle. In this way the temperature of the most vibrating particle is reduced a little bit after the collision, and the temperature of the less vibrant particle is increased a little bit.
If a long row of particles is ordered according to how much they vibrate, the particles will exchange vibrations so that the high temperature particle on one end is able to share its vibration intensity with the low temperature particle at the other end. This proceeds until all the particles vibrate the same.
The process of vibration exchange is called heat flow. And heat is the amount of vibration that one particle is able to give away to it's neighbour.
I think that to explain a complex concept it is useful to make a similitude with another system that the students can visualize easily in they experience.
In the case of heat and temperature, it is almost straightforward the similitude with bowls filled by water:
water volume > heat content
water height > temperature
This similitude can help to explain also the heat capacity: a cylindrical bowl with larger base reaches a lower height than a bowl with a smaller base.
But this similitude can explain also the dependence of the specific heat on the temperature: the bowl geometry determined by the section S as a function of the height h, S(h) correspond to dQ/dT.
Connecting the bowls can explain the equilibration of two bowls connected by a pipe in the bottom: what we have is that the heights reaches the same value and not the quantity of water.
Moreover, we can also explain the role of the formation energy, putting the base of two connected bowls at different height.
A question arises: there is a physical reason that makes hydrostatic (in gravity) and thermodynamics so similar? I think yes, because both systems represent a way of storing energy.
I like Gianpiero analogy, but I would say:
"water volume" = generalized energy: (internal energy, enthalpy)
"water height" = temperature
"heat" = amount of water that goes from one bowl to the other when they are connected by the pipe in the bottom.
@Noé
I agree with your amendment. Thanks, the make the analogy more precise.
From many of the detailed definitions found above: one might think good 'Ole Phlogiston theory makes a comeback!
Temperature is a scalar quantity, heat is an idealized vector transfer of energy; equally, temperature is a measure of the internal energy of a system. I agree that there is a finer gradation in definition, but this is purely semantics and metaphysics. Temperature is heat and vice versa... One example that flushes out the difference is turbulence, where one may not measure a temperature difference, because of the coarseness of measure with a thermometer; but, there is definitely heat transfer during the process.
In my line of work, bioeffects, we always talk about a finer thermometer and the need for such a device. There are now nano-particles being used to measure temperature on a nano-scale. One can take the limit and idealize an atomic size thermometer, then, once again, temperature is heat.
Anyway... much of Science is circular arguments. I always find the simpler explanations to be more meaningful, where tautologies provide nothing but headaches.
As was mentioned above, temperature is an intensive property, whereas energy is an extensive property. This means that by adding two bottles of water of the same temperature into a bucket, the resulting temperature is not doubled, but remains constant. Temperature is independent on the system size. The energy, however, of the content of the bucket is twice that of the content in one bottle. The energy content is proportional to the system size.
Hence, temperature and energy is not the same.
And it follows that heat, which is the transport of energy, is not the same as temperature either.
I should also point out that in some cases heat transfer happens at constant temperature such as phase transitions.
Yes, it is true. The isothermal expansion/compresion of an ideal gas occurs with no change in internal energy and the heat transferred between the system and the surroundings is equal to the work performed. Therefore, there is heat transfer with no difference in temperature (and an infinite heat capacity).
We often refer to infrared radiation as being primarily heat (or thermal) radiation. But what exactly is heat, and how does it differ from temperature? Simply put, heat is a measurement of energy. All molecules contain some amount of kinetic energy, that is to say, they have some intrinsic motion. The hotter an object is, the faster the motion of the molecules inside it. Thus, the heat of an object is the total energy of all the molecular motion inside that object. Temperature, on the other hand, is a measure of the average heat or thermal energy of themolecules in a substance. When we say an object has a temperature of 100 degrees C, for example, we do not mean that every single molecule has that exact thermal energy. In any substance, molecules are moving with a range of energies, and interacting with each other as well, which changes their energies. But if we average the thermal energies of all the molecules together, we can obtain an object's temperature
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