# Tag Info

Accepted

### Does color temperature limit how much a laser of a given wavelength can heat a target?

The argument for heating by the Sun is that if the target object is hotter than the Sun it would heat the Sun rather than the Sun heating it. We could try to apply this argument to a laser, but how ...
• 358k
Accepted

### Should I hold a baby formula bottle to cool it down faster?

Sure! I think I'm qualified to answer, not because I used to teach heat transfer in a Chemical Engineering course, but because I raised four daughters!! Air is an excellent thermal insulator. If you ...

### Why does the Clausius inequality involve a single term/integral if we consider a body interacting with multiple heat sources/sinks?

The $\delta Q_i's$ are not for different sources at the same time through the process; they assume that, at any one time, there is only one heat source or sink. The subscripted heats are for ...
• 34.1k

### Is non-temperature related Symmetry Breaking possible?

Temperature is not needed to define symmetry breaking. Symmetry breaking simply refers to the loss of some symmetry during the evolution of a system. Given that a system is in a state $A$ that is ...
• 1,091

### Does color temperature limit how much a laser of a given wavelength can heat a target?

Neither the Sun nor a laser are objects in thermodynamic equilibrium The second law of thermodynamics, which prohibits the flow of heat from a colder to a warmer object, applies to objects that have ...
• 60.4k

### Does color temperature limit how much a laser of a given wavelength can heat a target?

Assuming that the target is a black body. The real critical factor affecting heat transfer is emit energy per unit area described by Stefan–Boltzmann law $M=\sigma T^4$. The temperature increase ...
• 151
Accepted

### Why the Sun has a higher temperature than humans?

The thermal energy per gram of matter of the Sun is definitely higher than of humans, being between 6000K and 15000000K depending on where in the Sun. What you are probably thinking of is the fact ...
• 1,009
Accepted

### Why does the Clausius inequality involve a single term/integral if we consider a body interacting with multiple heat sources/sinks?

Note the circle on the integral sign. It means the integral is calculated over a cycle. Now, what is it in a heat engine (or a heat pump) that goes through a cycle? It is the working fluid: the gas/...
• 216

### Proportionality of Pressure and Temperature in defining Absolute Temperature scale

In defining the ideal gas temperature scale, it is assumed that the pressure of the gas at constant volume is proportional to the temperature $T$. How can we verify whether this is true or not? Are we ...

### Does color temperature limit how much a laser of a given wavelength can heat a target?

No, your reasoning does not apply to a laser. You can use Wien’s law to relate the peak emission wavelength to the temperature of a black body emitter (a perfect absorber/emitter across all ...
• 1,665

### Does color temperature limit how much a laser of a given wavelength can heat a target?

No, it is totally unrelated. Look at the National Ignition Facility (at LLNL). It has a laser, I do not know what its frequency is (probably a small multiple of $c/1064\,$nm, but it heats a pellet to ...
• 35.5k

### Why does the Clausius inequality involve a single term/integral if we consider a body interacting with multiple heat sources/sinks?

Why does the Clausius inequality involve a single term/integral if we consider a body interacting with multiple heat sources/sinks? The short answer is the integral allows you to do both discrete ...
• 73.7k

### Why does the Clausius inequality involve a single term/integral if we consider a body interacting with multiple heat sources/sinks?

Clausius inequality. Clausius inequality contains physical quantities of the system of interest, i.e. in $$\oint_{\ell} \frac{\delta Q}{T} \le 0 \ ,$$ $T$ is the temperature of the system (temperature ...
• 10.6k

### Is non-temperature related Symmetry Breaking possible?

In physics. Symmetry Breaking is related to temperature [...] Symmetry breaking in classical physics More correct way of saying this is that in (classical) physics symmetry breaking is related to a ...
• 60.4k

### Can metal get hotter than heat source?

Since steel melts at around 2500 $^0$F (1370 $^0$C) a 400 ($^0$C or $^0$F) flame would not melt steel. That aside, it would be impossible for a 400 degrees source to raise the temperature of a ...
• 73.7k
Accepted

### Feasibility of entropy at zero temperature

The first and most important part to this question is the link By Symmetry points out in the comments, which includes the following: The third law is equivalent to the statement that It is impossible ...
• 50.2k
Accepted

### Thermal spectrum of a warmer body in a colder room

Suppose I had a piece of glass (just as an example) at room temperature, let's say T0=293 K, and I moved it into a dark room that was TR=1 K. I assume the glass will radiate heat until it and the room ...
• 60.4k
Accepted

### Total differential of internal energy $U$ in terms of $p$ and $T$ using first law of thermodynamics in Fermi's Thermodynamics

Fermi was probably the last physicist who excelled as a theoretician and an experimentalist. His lectures inspired many students, who became outstanding physicists in turn. His textbook on ...

### How does the temperature of the condenser impact an air conditioner's energy usage?

if you had 5C cooling water you could possibly run the rest of the system as a heat pipe (if it were built the right way) Using rivers, the sea, ground water, the ground itself, and even swimming ...
• 906

### How does the temperature of the condenser impact an air conditioner's energy usage?

That makes intuitive sense, an AC doesn't have to work as hard if it's cold outside. It also makes sense when one considers the Carnot refrigeration coefficient of performance (COP), the theoretical ...
• 73.7k
1 vote

### The usage of temperature in quantum mechanics

Many-body quantum mechanics is also often referred to as Quantum statistical physics, which is a more telling name in the sense that it points out that we are considering systems where one has to take ...
• 60.4k
1 vote

### Can particles feel hot to the touch?

About the types of effect that atoms can have: An alpha particle is the nucleus of a Helium atom. In the case of a typical nuclear decay event the emitted alpha particle have a very low energy. Those ...
• 21.4k
1 vote
Accepted

### Two interacting blackbodies (one inside another) - when will thermal equilibrium be attained?

Here, the power emitted by $A$, $P_A$, is equal to the power supplied by the fusion reaction. Here is the mistake. In equilibrium the power emitted by $A$ is given by $P_{in}=P_{out}$, and the \$P_{in}...
• 103k
1 vote

### Is there any formula for calculating the temperature required for nuclear fusion for a specific pressure?

Key to getting the answer you wish is first knowing what the equation of state is for the fusion reactants. This lets you relate pressure, temperature, and density. Please note that all equations of ...
• 95.6k
1 vote
Accepted

### Is there any study of the temperature gradient at the surface of a liquid?

I’m not aware of any studies or experiments (have you done any research?), but it is logical that the temperature would be lower at the surface. Temperature is a measure of the average kinetic energy ...
• 73.7k
1 vote

### Does Pipe Temperature Directly Correlate To Water Temperature?

It's engineering: it depends on your requirements. Wherever there is heat flow, there will be a temperature difference. How much is acceptable? Copper is pretty conductive of heat: if you put an ...
• 21.8k
1 vote

### Should I hold a baby formula bottle to cool it down faster?

Liquid cooling is generally more efficient than air cooling for CPUs and car engines, even though a fan is used in the air cooling versions. In the case of the baby bottle we are not comparing the ...
• 6,182
1 vote

### Should I hold a baby formula bottle to cool it down faster?

Premise and suggestions Before answering your question, I'd like to do again the premise that this question and the comments in your question make from little to no sense to me. Anyway, beside the ...
• 10.6k
1 vote

### Besides the 2nd law of thermodynamics, what laws of optics prevent the temperature of the focal point of lens from being hotter than the light source?

My easiest argument was that the 2nd law of thermodynamics prevents this from happening because heat can't flow passively from a place of lower energy/entropy to a place of higher energy/entropy. He ...
• 39k
1 vote

### Chardonnay, air versus water

Let's break down the two parts of your problem step by step, considering the physics of heat transfer. Part A: Comparing Cooling of Wine Bottles in Freezer Air vs. Water 1. Cooling Mechanisms Bottle ...

Only top scored, non community-wiki answers of a minimum length are eligible