Tagged Questions

It's the physical property that indicates the degree/intensity of heat present in a substance or an object. It can be expressed and measured according to various scales.

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1answer
83 views

Are there reasons for the discrepancies in absolute temp units - Kelvin vs. kelvins vs. degrees Kelvin?

Before 1968, the units for absolute temperature were described as "degrees Kelvin" or "degrees absolute." After that, the SI system got rid of the idea of "degree" for absolute temperature, so the ...
3
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3answers
86 views

How could I determine the temperature at which an egg explodes

A while back, some friends and I pondered "what will happen to an egg if placed very near a campfire". So we placed an egg on a grill, approximately 12 inches above a real campfire. Something like ...
2
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2answers
118 views

Cloud chamber temperature

I'm planning to build a small cloud chamber. The design is the usual: alcohol evaporates at the top by gently heating it with a thin wire and small current. The vapour sinks to the bottom of the ...
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0answers
8 views

Temperature of air effused into tank - different predictions?

Consider air from outside at $T_0$ effusing into an evacuated and thermally isolated chamber. By thermodynamic potentials, the temperature inside the tank is given by: $$T_1 = \gamma T_0 = ...
0
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1answer
54 views

Exception to weight of hot vs cold water?

I have seen the various posts regarding the comparison of weight of heated and cold water.But is there any contradiction?I live in really hot conditions and as such tap water literally 'boils' ...
5
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1answer
114 views

Is temperature discrete

Because an object's temperature is inversely proportional to the wavelength of blackbody radiation which it emits, physicists have theorized the existence of Planck temperature at around $1.4×10^{32}$ ...
5
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1answer
113 views

Can water evaporate when frozen?

If an ice cube is stored in a freezer could it evaporate given enough time? Is there a temperature below which water cannot evaporate (even just a little)?
9
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2answers
408 views

If temperature is average KE per particle, and heat is total KE of all the particles, how can molar heat capacity vary?

If temperature is defined as the average kinetic energy per particle, and heat energy is defined as the total kinetic energy of all the particles (or more strictly, heat transferred is the total ...
15
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1answer
418 views

Why does a water drop on a hot plate at $150^o C$ evaporate faster than on a plate at $200^o C$?

I recently read that: "A drop of water landing on a hot plate at $150^o C \:(300 F)$ evaporates in a few seconds. A drop of water landing on a hot plate at $200^o C \:(400 F)$ survives a whole ...
3
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1answer
663 views

Behavior of water at temperatures above 100°C

Assuming you have container with heat insulation (something like boiler). You can store water at any temperature below 100°C. At these conditions, you can drill a hole into container and store water ...
2
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1answer
81 views

What causes a heat generating source to stabilize at a certain temperature? (Answered by myself, I think)

For example, we out a heat sink on a microprocessor to keep it cooler. I understand that if we run 100 watts of electricity through the microprocessor, it will generate 100 watts of heat, or 100 ...
0
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3answers
87 views

Is it possible to have $\Delta T\neq 0$ with no heat exchange $Q=0$, no work $W=0$ done, and no change in internal energy $\Delta E=0$?

Is it possible to have $Q=0$, $\Delta E=0$ and $W=0$, but $\Delta T\neq 0$? In particular, if there is no change in internal energy, doesn't that imply it is an isothermal process, and therefore that ...
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3answers
1k views

How does cold air move through a room

If you turn on a fan in a warm room, it feels as if cold air is being pushed from the fan out in the direction that it's facing, but what's actually happening on a molecular level? When an object is ...
1
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2answers
422 views

Temperature of ideal gas after volume increases in piston

A three part question, all related Part 1. My question is about an ideal gas in a rigid container with two (equal volume) compartments separated by a rigid wall. One compartment has an ideal gas at ...
4
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5answers
275 views

Would dropping large blocks of ice into the ocean mitigate global warming?

This amusing Futurama sketch 'solves' global warming by dropping increasingly larger blocks of ice into the ocean. Presumably the blocks of ice are harvested from a different planet. Would this ...
7
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2answers
387 views

Why is the absolute zero a rational number in Celcius?

From the question "Why is the absolute zero -273.15ºC?" I understood that 1°C is the 100th part of the difference of melting and boiling temperature of water (this is my high school physics, ...
3
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3answers
233 views

Why is the salad tray at the *bottom* of the fridge?

In a badly-adjusted (too cold) fridge, I notice that things like celery & lettuce are more likely to be spoiled by becoming frozen if they're put on a middle shelf, rather than the salad drawer at ...
11
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2answers
215 views

How loud is the thermal motion of air molecules?

In other words, given a magical room with walls that produce no vibration and transmit zero vibration from the outside, and nothing on the inside except room temperature air, what would be the noise ...
3
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3answers
295 views

Is there an upper limit to temperature in thermodynamics or statistical mechanics

In many presentations of statistical mechanics where we have a system of particles having mass, such as the molecules of an ideal gas, the temperature is often equated to the average relative velocity ...
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2answers
93 views

double of temperature

I'm not a physicist, but I was having a discussion with a friend and I could not convince her about the main point. I asked her: "If I am in a place which temperature is 10ºC and she is in a place ...
4
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3answers
77 views

How does temperature affect photovoltaics (PV) efficiency?

I know that photovoltaic panels are more efficient at lower temperatures: As the temperature increases, the output voltage decreases. I am looking for an explanation of the mechanism behind this ...
0
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1answer
134 views

Temperature in a Voltaic Cell

The potential difference across a voltaic cell varies with temperature. But my question is whether the voltage increases or decreases as temperature rises. According to the Nernst equation, the two ...
3
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1answer
83 views

The origin of the colour of the sun

I have learned so many concepts under astrophysics and unfortunately, I have muddled everything together... Let me try to illustrate my problem: When a star is in main sequence, it fuses hydrogen to ...
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1answer
543 views

Characteristic length for the diffusion equation (temperature)

The background: I'm doing some simulation work involving the diffusion equation in 1D. Specifically I have some temperature profile, constant thermal conductivity and fixed temperature at each end of ...
2
votes
1answer
121 views

Are Verdet Constants Temperature Dependent?

The Verdet constant of a magneto-optical material shows up in the calculation of the rotation of polarized light in a medium submerged in a magnetic field. The amount of rotation is given by $$ ...
5
votes
3answers
8k views

Does wrapping a wet paper towel around a glass bottle really speed up the cooling process?

There are claims like this one that you can improve the cooling speed of beverages when you put them wrapped in a wet paper towel inside the refrigerator/freezer. I've just tried it by myself and ...
1
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1answer
51 views

Do gases have a general upper limit of density?

Is there some limit for the density of gases, at which no change in condition could make it more dense without making it fluid, or solid - or something 'in between'?
2
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2answers
259 views

Why is the periodicity of fields in finite temperature QCD consequence of Trace in the action?

In finite temperature QCD, the gauge fields must be periodic in temporal direction. They say this is the consequence of trace in the action for gauge fields. How does trace imply that the fields must ...
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1answer
126 views

Examples to illustrate temperature dependant radiation by examples of temperature to color relation

I'm looking for a set of examples to illustrate the relation of temperature and color of "glowing" bodies. It should allow to build an intuitive understanding of this relation, so it's not about ...
3
votes
1answer
83 views

How is earth a magnet while it's volume is mostly above curie temperature?

I was assuming the earth's magnetism is similar to a permanent magnet; But below a depth of somewhere near the Mohorovičić discontinuity (Moho) between earth's crust and mantle it should be above ...
22
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9answers
9k views

How can water evaporate at room temperature? [duplicate]

Boiling point of water is 100 degree Celsius. The temperature at which water in liquid form is converted into gaseous form. Then how it possible for water to evaporate at room temperature?
0
votes
1answer
134 views

Time to heat/cool a room

So, I have a basic, very basic, understanding of thermodynamics. I don't take it until next semester. I'm attempting to write a program which plots a temperature over time graph of a room being ...
2
votes
1answer
167 views

Why does overclocking a CPU cause it to generate more heat?

It seems odd to me that overclocking a CPU causes it to consume more energy. The amount of energy flowing through the CPU should be related to the average number of 'gates' (or transistors) that ...
2
votes
4answers
51 views

Optimizing water boiling

I'm about to prepare some spaghettis and to do so I need 2 liter of boiling water. For getting the water to certain temperature (lets say 100 Celsius degrees) from a starting temperature of 15 ...
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4answers
239 views

Can a thermometer really measure the temperature of a substance?

When we measure the temperature of a substance by using a thermometer and waiting until the two come into thermal equilibrium, the thermometer will not display the original temperature of the ...
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2answers
42 views

Can temperature be objectively related to energy?

Temperature is disordered kinetic energy, with 0K being 0 Joules disordered kinetic energy, if I"m not mistaken. So, given required parameters(temperature, number of particles, mass of each particle, ...
2
votes
2answers
66 views

Temperature of gases

I can't find any law that states this (maybe the combined gas law does and I'm misinterpreting it?), but Feynman said that if you compress a gas, the temperature increases. This makes sense, for ...
2
votes
1answer
63 views

Enthalpy of vaporization

I've been thinking about refrigeration technology and am a bit confused about two common answers. Specifically, the part where the expansion valve releases the pressurized fluid and stuff gets real ...
3
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2answers
221 views

Can you extinguish a fire by cooling down the fuel?

I know that temperature plays a crucial role in the process of ignition, as most combustible materials will spontaneously start burning in presence of enough oxygen when heated above the kindling ...
2
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0answers
23 views

Quantum computing records (storage times)

Long storage times for qubits will be integral in the construction of a scalable quantum computer. This leads me to ask the current state of affairs in our ability to store qubits. Namely, what is the ...
3
votes
1answer
172 views

How do you explain the fact that when air expands freely into an evacuated chamber from a constant pressure atmosphere, its temperature increases?

I came across this paper: Baker, B. (1999). An easy to perform but often counterintuitive demonstration of gas expansion. American Journal of Physics, 67(8), 712-713. ...
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2answers
416 views

Physical significance of negative temperature

I read some answers regarding negative temperatures but I think my question is new. I want to know that what is the physical significance of negative temperature. Suppose I say a body has ...
0
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1answer
78 views

Comparing unknown temperature scales [closed]

Source: Principles of Physics by Resnick, Halliday, Walker. $9^{th}$ edition. Chapter 18. Problem 6. On a linear $X$ temperature scale, water freezes at $-125.0^0X$ and boils at $360.0^0X$. On a ...
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2answers
191 views

Acer saccharum (Sugar Maple) Sap & Freezing

This may or may not be the appropriate scientific discipline to ask this question of, but I'll give it a shot. I'll happily invite chemists to chime in as well. It's time to tap sugar maples in the ...
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2answers
152 views

If a planet were cut in half but stayed hemispherical, how hot would the ocean on the flat side be? [closed]

Some time ago I asked a question about gravity on a hemispherical planet. What would gravity be like on a hemispherical planet? Would the water all boil away at first, quickly cooling the core of ...
0
votes
1answer
50 views

Density as a function of Temperature?

I know that volume = mass/density....and density is the function of temperature. Is there any standard equation that describes density as a function of temperature? The system I am interested in is ...
0
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0answers
34 views

Techniques to cool gas to -100 celsius degrees

I am planning to design a scrubber system to separate CO2 and some other gases from a gas mixture. For this purpose, I thought to cool the gas below CO2's boiling point which is -57 Celsius. There are ...
0
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2answers
290 views

Auto-refrigeration

I'm reading about the auto-refrigeration effect and can't find a really good explanation. Is the idea that when you have your condensed liquid, and then release it into a low pressure environment, ...
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1answer
78 views

Fluid Temperature as a function of Mass and Ambient Temperature

Problem I am trying to create an equation to calculate fuel temperature based on ambient temperature, heat exchange rate, and mass. The idea is very simple; when the mass is heated, depending on how ...
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votes
2answers
356 views

Why does my kettle only make a noise when it is turned on

Almost as soon as I turn my kettle on it starts to make the familiar kettle noise, yet very shortly after turning off the power the boiling noise stops and the kettle is totally silent. The ...