# 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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### How to calculate heat emitted and the range

If I have a source of heat and I know it's surface temperature and size (suppose there are no barriers, only vacuum) can I then calculate the length to which the heat will be felt, and create a graph ...
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### How many neutrons would it take to boil a gallon of water? [closed]

How many neutrons would it take to boil a gallon of water?
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### How could I calculate the Heat Index with low humidity?

The formula shown in the Heat Index(HI) requires that the relative humidity should be equal to or greater than 40%, so how to calculate the heat index when the humidity is less than 40%? Or is there ...
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### Is it possible for dark energy density be decreasing? [closed]

I have an equation relating dark energy density and temperature, actually they have a linear relationship, my question is how to choose the temperature? If I choose the temperature of universe, the ...
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### Why do Temperatures Equalize

I have some Oxygen at Temp A in one container and some Nitrogen at Temp B in another container. If I mix these two containers eventually both the Oxygen and Nitrogen will be at the same temperature. ...
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### The Kelvin-Celsius problem

Let's suppose we have temperatures 30°C and 35°C. Converting them to Kelvin we have 303.15K and 308.15K. In the second case, the temperature difference is 5K. While in first case, temperature ...
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My calculations: $$Q_g + Q_l = 0$$ $$Q_g = -Q_l$$ $$mc\Delta T = -mc\Delta T$$ $$(0.05)(2100)(T_f+10) = -(0.4)(4200)(T_f-40)$$ $$105(T_f+10) = -1680(T_f-40)$$ $$105T_f + 1050 = -1680T_f + 67,200$$ $$... 3answers 85 views ### Degrees of freedom and temperature I quote the following lines directly from the Wikipedia page titled "Heat capacity": "...rotational kinetic energy of gas molecules stores heat energy in a way that increases heat capacity, since ... 2answers 34 views ### Diminishing solar temperature and its effects on earth This is a hypothetical question; considering both the earth and the sun as black bodies. If the temperature of the sun decreased N times, what would be the effect on the radiation intensity received ... 3answers 124 views ### Gross “temperature” of a globular cluster Globular clusters can be very large, which means we can do statistics about the stars in them. And that means we can try matching their star-as-particle potential/kinetic energy distribution against ... 2answers 267 views ### Can a black hole have negative temperature? Stephen Hawking said that black hole also have temperature and it is related to its mass so in other words a black hole can also be shown to have a negative temperature! I know that nothing is colder ... 0answers 30 views ### What is the smallest practical milliKelvin temperature sensor or technique? I need to track the temperature of a mass of less than 1 gram, and the two constraints are accuracy and mass of the attached sensor/circuitry (it must be less than 1.5g). Ideally it should be a non ... 2answers 85 views ### Does contracted spring weigh more than stretched one? (One of examples that potential energy contributes to mass.) Does hot object weigh more than cold one? (One of examples that kinetic energy contributes to mass.) If these are true and justified by ... 2answers 100 views ### Intuitive explanation of the shape of the Maxwell-Boltzmann distribution At higher temperatures (for an ideal gas), the Maxwell-Boltzmann distribution is spread more widely and has a lower maximum. At lower temperatures, the spread is much more narrow and the peak is much ... 4answers 453 views ### Mass in special relativity? Is the mass of a object at rest defined by$$E=mc^2$$where m is the rest mass. I.e. does the rest mass include every thing from thermal to gravitational potential energy and every other possible ... 1answer 7k views ### Mixing Water at Different Temperature If I have cup of water at room temperature (say, 25^\circC). What would be the resultant temperature if I pour another cup of same amount of water at 100^\circC to it? Is it simply \frac{25+100}... 2answers 86 views ### Is Moon too hot? I find it puzzling that Moon's maximum "daily" equatorial temperature is almost 400K. Earth's theoretical black body temperature would be 279K at 1AU, and Moon is the same distance from Sun, yet its ... 2answers 926 views ### Why do electron and hole mobilities decrease with temperature? From page 35 of "Microelectronics" by Millman Grabel Mobility \mu decreases with temperature because more carriers are present and these carriers are more energetic at higher temperatures. ... 5answers 2k views ### Milk or sugar first to maximize temperature of a hot cup of tea? If there is a hot cup of tea and we were asked to add milk and sugar, which mixing order would make the hottest tea? I personally think that the order doesn't matter, since sugar wouldn't change the ... 1answer 30 views ### Temperature of the System right after mixing water at different temperature Let's assume that 100gm of water at temperature 25^{\circ}C and another of 300gm at 90^{\circ}C. After mixing both samples, we would eventually get a constant temperature (say T^{\circ}_f) and ... 2answers 46 views ### Why does hot water gets cooler on stirring instead it should have gotten hotter When we keep on stirring hot water vigorously it starts getting cooler. But we are increasing the random kinetic energy of the molecules of water. Heat is as it is the energy of RANDOM motion of atoms.... 2answers 716 views ### How fast will 1 Liter of 65°C water get back to 20°C? I want to make a very simple example for a PID controller (to learn and understand it). I thought of a controller for a water boiler. 1 liter of water in the boiler is in a 20°C room (fixed ... 1answer 51 views ### Newton's Law of Cooling [closed] As shown in Figure 3.3.11, a small metal bar is placed inside container A, and container A then is placed within a much larger container B. As the metal bar cools, the ambient temperature T_A(t) of ... 0answers 25 views ### Is there a limit to how hot an object can be? [duplicate] We know that speed of physical object cant exceed speed of light, a body cant be cooler than 0k, thus does there exist a limit to hotness of an object? 2answers 67 views ### Why water's temperature is less than air? I measured the temperature of water and found that it's less than room temperature. I think evaporation is the main reason of it. Are there any reason except evaporation for the less temperature of ... 3answers 55 views ### Heat transfer between water tank and room temperature I have 20 gallons of water (salt water, but this might be irrelevant). These 20 gallons have a heater that maintains a minimum of 78º F. With the increasing temperatures during summer, the water ... 0answers 44 views ### Air preasure vs temperature [closed] Suppose you have a container of 1 liter of air at sea level with an initial pressure of 1 atmosphere. How high could the pressure get by only raising the temperature. Is there a point (providing the ... 3answers 339 views ### Why does S = k_B \ln W not always apply? I thought for a long time that the Boltzmann formula for entropy, S = k_B \ln W, was a universally true statement, or rather the definition of entropy from the perspective of statistical mechanics. ... 1answer 40 views ### What is the source of the Curie point? I'm seriously revisiting my knowledge on magnetism, and the Curie point has been both enlightening and mystifying. I understand what it does ((ferro)magnetism disappears above it), and have a faint ... 3answers 43 views ### Wind restistance as function of temperature Is temperature-dependent wind resistance the reason there's a significant increase in fuel consumption in my Prius car when air temperature drops by 30 degrees K from 300 degrees K? I think I see a ... 1answer 24 views ### Phase diagrams and critical pressure If a solid substance is pressurized past its critical pressure, what happens? Is the critical pressure only a factor when a substance is over the critical temperature also? On another note what makes ... 5answers 5k views ### What happens when I place an ice cube into boiling water My friend tried this experiment at home: She put an ice cube into boiling water. The water in the container stops boiling while the ice melts to water. My question: Why does the water stop boiling ... 0answers 44 views ### Cooling of salt on a conveyor belt Hi there and thanks in advance! My name is Chris, I'm a chemist who's been put in charge of getting the boss's new salt plant running smoothly. He owns several small companies and I'm the closest ... 1answer 141 views ### Quantum field theory: zero vs. finite temperature I have recently been made aware of the concept of thermal field theory, in which the introductory statement for its motivation is that "ordinary" quantum field theory (QFT) is formulated at zero ... 1answer 31 views ### Is there a limit to the difference between the boiling and melting points of any material? Is there a mathematical limit to the difference in the temperatures, a substance acquires before changing states, in this particular case, is there a limit to the difference between the boiling and ... 0answers 25 views ### Color Temperature Variation of Sunlight I want to know what is the Variation of the color temperature in Kelvin of Sunlight as viewed from the earth from Sunrise to Brightday to Noon to Sunset. Will there be any change in the color ... 6answers 2k views ### Why does the bathroom become hot after a bath? I have noticed many times that whenever I enter into the bathroom just after someone else bathed the temperature inside it would be high. Is it that the body heat comes out when we pour a lot of ... 0answers 18 views ### Experiments on the melting of snow? When snow melts there are three main variables: the temperature of the air, the altitude of the sun, and the distance of the sun from the earth (which changes because the earth moves in an ellipse ... 2answers 25 views ### Consequences of T_{sat} and P_{sat} dependence I understand that boiling point increases as pressure increases. This means that if you boil water at higher pressure it is going to need much more energy to break the bonds and thus boil at higher ... 5answers 18k views ### What is the effect of an increase in pressure on latent heat of vaporization? What is latent heat of vaporization (L_v) in the first place? Wikipedia seems to indicate that it is the energy used in overcoming intermolecular interactions, without taking into account at all any ... 0answers 64 views ### Are there any liquid that becomes solid on heating under room temperature? The title says it all. When I searched around, there are answers which involve extra steps like super cooling and then heating or exposing the liquid to high pressure. But I would like to know if ... 2answers 300 views ### Is there a limit to how hot an object can get? If heat is the measure of how fast the atoms are moving in an object, than isn't there a limit to how hot that object can get as nothing can go as faster than the speed of light. So because the atoms ... 7answers 6k views ### Why is there no absolute maximum temperature? If temperature makes particles vibrate faster, and movement is limited by the speed of light, then temperature must be limited as well I would assume. Why there is no limits? 1answer 62 views ### Rate of change of temperature of the Universe Temperature of the whole universe is about 2.7K base on the wmap satellite. I know that temperature has to decrease to time and I have difficult time finding references for rate of change of ... 1answer 956 views ### What leads to the existence of critical temperature? We know that T_c is the temperature above which no amount of pressure could force a gas to liquefy. But why is this? Somehow I don't buy the point that the gas molecules exert too much pressure ... 0answers 37 views ### Why do different color materal differ temperature in the same sunlight? I have a blue, red, and green cup and put a thermometer in each. Of the 3 the blue cup had the coldest temperature inside, then green, then red. I understand there may be differences in the ... 1answer 217 views ### The difference in how temperature feels inside in the summer vs. in the winter? 72 degrees feels cooler when it's hotter outside, say 90 F but warmer if it's really cold outside, say 32F However it also feels different if it's 90 vs say 70F outside. Why is that? 1answer 36 views ### How the mechanical equivalent of heat is employed in this situation? Reading a little about the "mechanical equivalent of heat" what I understood is that we can convert units between calorie and J by setting$$1\mathrm{\ J} =4.1860 \mathrm{ \ cal}. Now, I saw a ...
Objects can be categorized as blackbodies (emissivity $\epsilon = 1$), grey bodies (emissivity $\epsilon < 1$) and white bodies (emissivity $\epsilon = 0$). If we placed two objects (identical ...