What is Temperature: Definition and 1000 Discussions

Temperature is a physical quantity that expresses hot and cold. It is the manifestation of thermal energy, present in all matter, which is the source of the occurrence of heat, a flow of energy, when a body is in contact with another that is colder or hotter.
Temperature is measured with a thermometer. Thermometers are calibrated in various temperature scales that historically have used various reference points and thermometric substances for definition. The most common scales are the Celsius scale (formerly called centigrade, denoted as °C), the Fahrenheit scale (denoted as °F), and the Kelvin scale (denoted as K), the last of which is predominantly used for scientific purposes by conventions of the International System of Units (SI).
The lowest theoretical temperature is absolute zero, at which no more thermal energy can be extracted from a body. Experimentally, it can only be approached very closely (100 pK), but not reached, which is recognized in the third law of thermodynamics.
Temperature is important in all fields of natural science, including physics, chemistry, Earth science, astronomy, medicine, biology, ecology, material science, metallurgy, mechanical engineering and geography as well as most aspects of daily life.

View More On Wikipedia.org
Recent contents Top users
  1. Evo

    Article in Nature On Global Temperature variability

    Interesting Article in Nature and looks like better news (as opposed to doom and gloom) things may not be as bad as previously predicted. It will be interesting to follow further research as we gain more data and produce more accurate climate predictions. Unfortunately, the article itself is...
  2. R

    Time to warm a volume of air to room temperature in a container

    Positing an empty container, underground, with a static temperature of 50F (both container, earth, and air temperature) and a volume of X... and introducing (and displacing) into this container a parcel of 30F air of volume Y (which is less than the volume of X)... Is there any way to...
  3. M

    Feeding temperature profile from experimental data into MAXWELL

    Hi All, my aim is to find the thermal conductivity of litz wire and also convection coefficient of litz wire and air. So, I am running experimental analysis (10A current into litz wire) and capturing the temperature of litz wire. So, I have temperature profile versus time for litz wire. Would...
  4. clembo

    Transformer exceeding its rated maximum temperature

    Homework Statement An oil-filled transformer has a c.m.r. of 500 kVA which allows it to run continuously in an ambient of 35°C with an oil temperature rise of 50°C. The transformer has a time constant of 1.5. hours and the ratio of copper losses to iron losses at c.m.r. is 1.5:1. After...
  5. P

    Study of effects of temperature on steel drilling performance

    When drilling a thick peace of steel I noticed the drill bit would cut through much faster when it was cool. The difference was minutes versus seconds! Is this a known phenomena in machining or was my drill bit simply contaminated with something or maybe other factors played a role? I've heard...
  6. lavendly

    Final temperature of the water after adding heat?

    Homework Statement You add 1500 cal of heat to a cup of water at 22.5ºC. The water has a mass of 500.0g. What is the final temperature of the water? Homework Equations Q=mcΔT The Attempt at a Solution so i tried solving it by finding the energy of the water Q=(500g)(1.0cal/g)(22.5ºC) Q=11250...
  7. P

    Calculate the temperature of neutrons emerging from a reactor

    Homework Statement A collimated beam of thermal neutrons emerges from a nuclear reactor and passes through a speed selector into a detector. The number of neutrons detected in a second with speeds in the range 4000 to 4010 m s−1 is twice as large as the number per second detected with speeds in...
  8. HelloCthulhu

    The relationship btw dielectric strength and temperature

    Wiki suggests dielectric strength is temperature dependent, but I've yet to find any math supporting this. I found some math corroborating a relationship between conductivity and temperature, but whether or not there's any causality between conductivity and dielectric strength has eluded me. Any...
  9. S

    Voltage equivalent of temperature

    How is voltage equivalent of temperature(Vt=KT/q) defined and derived? Is it related to kinetic energy(which is equal to 3kT/2)?
  10. E

    Air motor: temperature of exhaust

    I have an industrial application where 20kW of heat is being wasted, which is painful to watch. I have learned already that low temperature turbines just don't work, so would like to check some ideas and better understand how air motors/turbines work. I have also learned so far that...
  11. A

    Piston with crankshaft: what is the temperature of gas entering the cylinder?

    Homework Statement Homework EquationsThe Attempt at a Solution e) I know the temperature is lower in the transparent container but how do you represent this
  12. Luke Strand

    Finding Initial Temperature Entropy and Heat Exchange

    Homework Statement A 2.45 kg aluminium pan at 155 C is plunged into 3.58 kg of water. If the entropy change of the system is 162 J/k, what is the initial temperature of the water? Homework Equations Q = mcΔT ΔS=mcln(T_2/T_1) Q_water + Q_Aluminium = 0 c water = 4184 J/kg*K c aluminium = 900...
  13. F

    Temperature of Space: Atomic/Molecular Motion & Equilibria

    Temperature is atomic/molecular motion. However, the temperature of planetary surfaces without an atmosphere are often quoted. For example, the temperature of the lunar surface ranges from about -200 F to +200 F depending on whether or not the surface is exposed to the sun or is in shadow...
  14. C

    Which Type of Geothermal Power System is the Best?

    There are three geothermal systems that are commonly used: sry steam, flash steam, and binary cycle https://www.eia.gov/energyexplained/index.cfm?page=geothermal_power_plants . What are the efficiencies of the plants from best to least effecient on average?
  15. S

    How to calculate ambient temperature in space or in orbit?

    How would I go about calculating the ambient temperature in low Earth orbit (LEO) at approximately 400 km? What equations should I be referencing to determine the temperature of sun light side and/or eclipse side? Thanks!
  16. M

    Change in temperature for a system with entropy change

    Homework Statement I am Pretty Lost with this problem...[/B] A 2.45-kg aluminum pan at 155∘C is plunged into 3.58 kg of water. If the entropy change of the system is 162 J/K, what was the initial temperature of the water? NOTE:We did not receive a Tf for the system. Homework Equations...
  17. EastWindBreaks

    How to find specific volume given temperature?

    Homework Statement Homework Equations The Attempt at a Solution I don't understand how the solution got its values, not from the tables right? because I couldn't find such value from all of the tables. Since the pressure is less than the saturated pressure at given temperature, it is in...
  18. Vivek098

    Kelvin and Platinum Temperature Scale.

    Is it possible that Kelvin and Platinum Temperature Scale give same reading of Temperature?
  19. S

    Thermodynamics - Temperature change of Argon

    Homework Statement The temperature of n = 19 mol of argon gas is increased from T1 = 21 oC by Q = 4.4 kJ heat transfer, while the gas pressure is kept constant. What is the new gas temperature in Celsius degrees? Homework Equations and as its a monoatomic gas I think this means that the...
  20. Jamie_Pi

    Calculate Final volume and temperature of piston

    Homework Statement One cylinder in the diesel engine of a truck has an initial volume of 640 cm3. Air is admitted to the cylinder at 30°C and a pressure of 1.0 atm. The piston rod then does 500 J of work to rapidly compress the air. What are its final temperature and volume? Homework Equations...
  21. J

    I Schwinger effect verified by Unruh temperature?

    According to https://arxiv.org/abs/1407.4569, equation (2.15), the Schwinger electron-positron pair production rate in Minkowski space, ##N_S##, is given in natural units by $$N_S=\exp(-\frac{m}{2T_U})$$ where the `Unruh temperature for the accelerating charge', ##T_U##, is given by...
  22. M

    Climate Change: Why Doesn't Rising Temperature Balance Out?

    First, I am not a scientist, so this may be a stupid question. But with all the concern about global warming - and given that temperature and pressure are related - why doesn’t rising temperature cause the atmosphere to expand outward and the temperature to fall as a result, back to an...
  23. G

    Change in Temperature for Stretched Surface

    Homework Statement The surface tension of a layer of water obeys ## \sigma = a- bT##, where ##T## is the temperature. Find the change in temperaure, ##\Delta T## when the area is increased isentropically. Homework Equations ## dU = dQ -dW## , ##dW = \sigma dA##, ##dU = C_A dT + [\sigma...
  24. J

    Cooler objects able to increase the temperature of warmer objects?

    Not sure this should go here (you guys need a thermodynamics section). But there is quite the debate going on about cooler objects being able to increase the temperature of warmer objects here: https://wattsupwiththat.com/2017/11/24/can-a-cold-object-warm-a-hot-object/comment-page-1 They are...
  25. C

    Absolute zero temperature is impossible to achieve?

    Just a general musing. Could absolute zero ever be physically possible or is it like the speed of light but for an inverse reason? The speed of light take infinite energy to achieve. So therefore is impossible because the energy put into the system adds mass. This is not noticeable at slower...
  26. S

    Straight line plot of bipolar transistor - temperature?

    Hey everyone, I'm trying to plot a straight line for a bipolar junction transistor to find the room temperature, T, using my experimental results for the associated base-emitter voltage, ##{V}_{BE}## and collector current, ##I_C##. Here's the equation that I'm using: $$ I_C = α_F {I}_{EO}...
  27. S

    Solving for Final Equilibrium Temperature of Water-Copper System

    Homework Statement 173 g of water at 20°C is contained in a copper container of mass 327 g. An additional 129 g of water at 100°C is added. What is the final equilibrium temperature (in degrees C) if we treat the system's water and container as isolated? Homework Equations Q = mcΔT The...
  28. H

    Mean Earth Temperature Data: 1951-2012

    Data for the mean Earth temperatur: - For example, the average annual temperature for the globe between 1951 and 1980 was around 57.2 degrees Fahrenheit (14 degrees Celsius). (UCAR). - The global mean surface temperature is 14.46 °C computed from MODIS data (2001-2012). - Estimated Jan 1951-Dec...
  29. BillTre

    What is the Science Behind Temperature Control Fabric?

    This article in Science mag news is about a fabric that can, let more heat (via IR) out in hot weather, or flipped over, keep more heat in the cold Here is the Science article (not free). The fabric also let's gasses and humidity pass through because it has nano-pores. It has 4 layers: 2...
  30. J

    Unsure Regarding Temperature Model for an Open System

    Hi guys, I am currently working on my master thesis. I am supposed to make a dynamic model for a gas system and have some trouble setting up the energy balance. I am a noob when it comes to uploading pictures, so I don't have a figure for this, but let's consider a general control volume (CV)...
  31. V

    Thermodynamics Final Temperature of Water

    Homework Statement A certain mass of water in a copper pot is heated over a stove that releases joules of heat to heat the water. Later the same mass of water in an aluminum pot is heated over another stove that releases the same amount of heat in order to heat the water. Then the water in...
  32. AlexanderinCbus

    Question from a layperson: Particles & temperature

    Hello! First post here so go easy on me. I am a Physics enthusiast, but I fear I am a layperson when it comes to the field. Most of what I know comes from low level college classes and the youtube channel PBS Spacetime. I have a question that might be a ridiculous one. But here goes. (Go easy...
  33. M

    Questions about Subsolar Temperature

    1. The problem statement, all variables, and given/known data I'm having a little trouble understanding planetary subsolar temperatures. The first equation comes from viewing the absorbing and radiating areas of an object as the same and the second equation comes from viewing the absorbing area...
  34. B

    Velocity in microchannel with temporal temperature variation

    a microchannel of length 2L and width h in the thermal cycling region. the temperature profile ...(1) the cyclic temperature profile leads to a time dependent density ...(2) using the mass conservation equation i.e. ...(3) and momentum balance equation i.e. ...(4) we have to find the exact...
  35. M

    Calculating Temperature Change for Heat Exchanger

    Hello, After the last post I completely changed the system. I now have a new system. Based on the feedback from last time I increased the time in contact with the block significantly. And I have made it a two stage unit. Here are the parameters for the first stage. An Aluminum block. (assume...
  36. R

    Can dissolving minerals affect water temperature?

    Are there any type of minerals/molecules/elements even solids that when dissolved, in say a glass of room temp water, can raise or lower the temperature? Examples...
  37. M

    Maintaining Magnetism at High Temperature

    The only way for me to move 1200 degree steel is with a magnet. The magnet loses its magnetism at 800 degrees, though, causing some pieces to fall and potentially injure people. Is there a way to electrically boost the magnetism of an existing magnet, apply an additional field to the magnet...
  38. H

    Ideal Gas Equation and Temperature change?

    During a thermodynamic process, the state variables of an ideal gas, measured in kPa, m3, and oC, varied in the following way: P2 = 2P1 V2 = 3V1 T2 = 8T1 What is the temperature increase of the gas, T2 −T1 ? I've been given an answer of 4780 and I'm not sure how to get there?
  39. EastWindBreaks

    How to find internal energy with constant temperature?

    Homework Statement since specific heat c changes with temperature, but its treated as a constant in the heat formula, so that means that heat formula Q=mc(T2-T1) is just an approximation? correct? I see some texts define heat as Heat, q, is thermal energy transferred from a hotter system to a...
  40. EastWindBreaks

    How to find internal energy with constant temperature?

    since specific heat c changes with temperature, but its treated as a constant in the heat formula, so that means that heat formula Q=mc(T2-T1) is just an approximation? correct? I see some texts define heat as Heat, q, is thermal energy transferred from a hotter system to a cooler system that...
  41. J

    Pressure, Volume, and Temperature at a Point in a Thermodynamic Cycle

    Homework Statement Question: https://imgur.com/a/8rUw1 Graph: https://imgur.com/a/Z1oBO Homework Equations Answer for Q1 (Just the formula) : https://imgur.com/a/uesqN The Attempt at a Solution I have realized that from 1-2, there is an increase in pressure, decrease in volume and increase...
  42. T

    Temperature and magnetic flux density

    Hello all; I am new in this forum, currently in High School. For some time now, I have been looking online for a relationship between temperature and magnetic flux density of a ferromagnet; below the Curie point. However, I can't seem to find any relationship or formula. Do any of you know...
  43. S

    Saturated VapourPressure of Steam above Critical Temperature

    Hello all, I am not sure my question will totally make sense for those of you who now this topic well but as I am new to it I hope I can be forgiven. My problem is to work out how much water will condensate as a stream of moist air is expanded through a turbine. So far I was using Antoine's...
  44. M

    How long does it take to heat a vessel?

    Homework Statement I need to find the time it takes to heat a vessel of water which is closed. Here is what I have: Specific heat capacity of water: 4184 J kg^-1 K^-1 Density of water: 1000 kg m^-3 Volume of water added and volume of vessel: 500 L or 0.5 m^3 Heat capacity of the vessel: 91000...
  45. K

    Why Does the Chain Rule in Thermodynamics Include a Negative Sign?

    I'm trying to understand why $$\left(\frac{\partial P}{\partial T}\right)_V = -\left(\frac{\partial P}{\partial V}\right)_T \left(\frac{\partial V}{\partial T}\right)_P$$ where does the minus sign come from?
  46. N

    B Do temperature and gravity affect particle or nuclear decay?

    I thought of another question(s) :) does temperature affect the rate of the decay at all? Does temperature effect the energy of the decay; in that the energy of the electron anti neutrino would be higher?
  47. K

    Calculating the maximum temperature of a heating wire

    <mod: moved from intro> Hello all! This is my first post in this forum. I am struggling with the following question regarding a hair dryer. The hairdryer can be seen as a cilinder with a fan inside blowing air at speeds from the table below and 1 nichrome wire which heats up consuming different...
  48. S

    Liquid temperature under pressure

    Hello, I have a question regarding bath pasteurising cider in bottles. The bottles are carbonated with CO2 and capped, I heat the water up to a temperature of 70deg.C I use a test bottle filled with water and with a cork in the top, I use this to monitor the temperature inside the bottle. So my...
  49. Muthumanimaran

    What is the Maximum Temperature for a Copper Block at 1000 atm Pressure?

    Homework Statement (a) A block of copper at a pressure of 1 atm and a temperature of 5 degree celcuis is kept at constant volume. If the temperature is raised to 10 degree celcius what will be the final pressure? (b) If the vessel holding the block of copper has a negligibly small thermal...
  50. F

    Stationary temperature field inside a house

    Homework Statement House: a room (see figure) has perfectly isolated walls, except the two windows where a convective heat exchange takes place (with the same transfer coefficient). Outside temperature in front of a sun-faced wall-sized panoramic window is T1, while at the back it is...
Back
Top