Temperature Definition and 1000 Threads

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.

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  1. M

    MHB What Is the Temperature Coefficient of a Car Battery Resistor at 0 Degrees?

    Starting a car: the voltage drops from 12V to 7.2 V, it is 0 degrees out, and 150 amps are pulled from the car. What is the temperature coefficient of the resistor? I have NO idea how to do this. Help please!
  2. M

    MHB Tutoring for voltage, charge, terminal voltage drop , temperature coefficient.

    I have several problems regarding this/these topics. Is anyone available to tutor me right now? Thank you.
  3. Xoloti

    Train Whistle Echo: Calculating Distance & Temperature Effects

    Homework Statement a)a stationary railroad whistle is sounded. An echo is heard 4.0 seconds later by a train's engineer. If the speed of sound is 343 m/s, how far away is the reflecting surface? b) If the temperature of the air increased, how would this change your answer? Homework Equations...
  4. derekgabs

    Temperature change at a given time

    Good day to all, Hi, i would like to ask if there is a way to calculate the temperature change at a given time. I will use this as a basis for my study which is about designing an ice container and i would like to know how long does my ice last given its own temperature and the outside...
  5. G

    Wall temperature in heat exchanger

    My notes, using an example of a cold tube-side liquid cooling down a hot shell-side liquid stated that: ΔTb = TbS-TbT Mean tube-side wall temperature: TwT=TbT+(tube-side film resistance)/(total resistance) * ΔTb Mean shell-side wall temperature: TwS=TbS-(shell-side film resistance)/(total...
  6. U

    Temperature change of Water after dropping a ball into it

    Homework Statement Suppose we drop a lead ball of mass M into water of mass m from a height h and allow everything to settle down. What is the temperature change of the water? Assume that the container is well insulated. Homework Equations Potential Energy = mgh dU = mcdT where dU is the...
  7. I

    Cooling/heating temperature rate change

    Ok, so I could do an experiment on this first, but I decided to see if anyone knew beforehand. So basically my question is will different properties of the same temperature, exposed to the same temperature, cool/heat at the same rate? For example would a more viscous liquid cool as fast as...
  8. S

    Automotive Car Wheel Temp: Brake Rotor & Hub Heat Range

    Considering how hot brake rotors get under hard street and race track braking, what is the typical heat range experienced buy the actual wheel in contact with the rotor and hub?
  9. M

    Water and Ice mixture, Find original temperature of water

    Homework Statement An 8 cm3 ice cube (temperature = 0.00 °C) is dropped into a glass with 3 dL juice which results in the ice cube being melted. By doing this, the juice drops to a temperature of 3.00 °C. What was the temperature of the juice before the ice cube was added? (Treat juice as water...
  10. C

    How to Calculate Power to Maintain a Cooling Stream at 46°C?

    I have a combustion process, and have calculated the net enthalpy of my inlets and outlets. Some of the energy released by the combustion is used to heat a cooling stream, maintained at temperature 46degC. I wish to calculate the power required to maintain this cooling stream temperature: I was...
  11. kiwaho

    I Is there way to thermalize an electron to room temperature?

    At room temperature, particle energy is 0.025eV. Neutron capture reaction has big cross section when neutron is in room temperature. Theoretically, so does an electron. At 0.025eV, the electron velocity should be only 93.78km/s. Unfortunately almost no way to cool down an free electron to so...
  12. S

    The change in temperature of moist air

    Homework Statement 1 kg of moist air and 1 g condenses. What will the change in the temperature of the moist air be? Heat of Vaporization = 2.5*10^6 J/kg 2. The attempt at a solution The moist air will warm due to condensation. Heat of Vaporization=2.5*10^3 J/g Specific heat at...
  13. W

    Looking for resistivity vs. temperature lab charts

    Hi everyone, I am looking for basic elements resistivity vs. temperature laboratory measurements charts. Anyone has ideas where to look for? Regards
  14. TheSodesa

    Temperature as a function of 3 variables....

    Mod note: moved from non-HW forum section Apparently doing math homework on Physics Forums helps me think more clearly. The d-part of this question gave me a headache, and I already wrote all of this LaTeX code on the homework side of this site, so I figured I'd post it even though I solved it...
  15. B

    How to graph a linear relationship between T and v of sound?

    Homework Statement I did an experiment involving the speed of sound at different temperatures. I placed two microphones at a fixed distance apart and I measured the time taken for a sound wave to travel between the two mics. I repeated this for different temperatures. I want to make a graph for...
  16. S

    Calculate the change of temperature in terms of T

    Two Thermally insulated cylinders, A and B, of equal volume, both equipped with pistons, are connected by a valve. Initially A has its piston fully withdrawn and contains a perfect monatomic gas at temperature T, while B has its piston fully inserted, and the valve is closed. Calculate the final...
  17. N

    How to find variation of modulus of rubber with temperature?

    I want to know the what is the effect of temperature on modulus of rubber, mathematical expression will be helpful
  18. G

    Temperature increase with stirring?

    Let's say that I have a spoon and a cup of coofee, I stir it with the spoon does its temperature decrease or increase ? (There is friction force so a bit of energy should turn into heat but it's strange).
  19. RJLiberator

    Thermal Equilibrium Temperature Question Sodium and Water

    Homework Statement Expose the error: When sodium is placed in water, a violent reaction always occurs; therefore sodium and water can never be at the same temperature. Homework Equations Thermal equilibrium and temperature. Zeroth law. Isotherms. The Attempt at a Solution My Answer: The...
  20. ramzerimar

    Numerically find temperature in function of concentration....

    Homework Statement I don't even know if this is the correct forum for this question, but here we go. This exercise is from my numerical methods for engineers class, and it says the following: The coefficient of saturation of oxygen dissolved in fresh water is given by the equation: $$...
  21. Henry Stonebury

    Thermodynamics: Pressure and temperature from turbine

    Homework Statement A turbine is receiving air from a combuster inside of an aircraft engine. At the inlet of the turbine I know that T1 = 1273 K and P1 = 549 KPa, and the velocity of the air is essentially 0. The turbine is assumed to be ideal, so its efficiency is exactly 1. Also: R = 287...
  22. nazmus sakib

    Does any kind of polarized light transfer heat?

    Does any kind of polarized light transfer heat or any other form of energy? If possible give me some theory and related equation.
  23. Idrees Afridi

    Temperature gradient vs thermal boundary layer thickness

    what does the relation between the temperature gradient inside the thermal boundary and thermal boundary layer thickness i mean what will be the temperature gradient ( high or low) when the thermal boundary layer is thick relative to the thin one? Kindly explain mathematically and physically as...
  24. Revengeance

    Calculating Tire Pressure Change with Temperature Increase

    An automobile tire has a pressure of 210kPa at 20.0 degrees celsius. What will be the tire pressure after driving for some time if the temperature rises to 35.0 degrees celsius. The equations we have are P1*V1/T1 = P2V2/T2 V1/T1=V2/T2
  25. M

    How Do Volume Expansions Differ in Liquids and Gases Due to Temperature Change?

    What are two aspects in which the volume expansion of liquids and the volume expansion of gases due to a temperature change vary? Answer: One of the aspects is that gases can be more easily heated than liquids. This is because there are intermolecular forces (Van Der Waals interactions)...
  26. Octet

    As water depth increases, does temperature go below 0C?

    After passing the thermocline, in which water temperature decreases rapidly over short distances, temperature falls into a sort of constant-looking decline. However, looking at the graph, it looks almost asymptotic. I've not been able to find a chart measuring water depths below 10,000m, so I'm...
  27. E

    Specific heat capacity of a metal at low temperature

    Homework Statement The specific heat capacity of a metal at low temperature (T) is given as ##C_p = 32\left({\dfrac{T}{400}}\right)^3## (kJK-1kg-1). A 100g vessel of this metal is to be cooled from 20 K to 4 K by a special refrigerator operating at room temperature (27°C). The amount of work...
  28. wolram

    B Final Temperature of the Universe: Effects of Dark Energy and Spatial Curvature

    I know there are a few ways the universe can end, if it ever does, but at what temperature would the universe be in after heat death?
  29. K

    Does electrical arc with the same power have same temp?

    Does electrical arc with the same power but different voltage and current have same temperature? When electrical arc is form, it is estimate that the temperature is about 3000K Does temperature depend on voltage or current alone? Or does it depend on power(P=VA)? I think it is power, because...
  30. E

    Cooking Gas Containers: Temp Impact of Motion

    Homework Statement Cooking gas containers are kept in a lorry moving with uniform speed. The temperature of the gas molecules inside the containers will increase, decrease or stay the same? Homework Equations T is proportional to KE of gas molecules. The Attempt at a Solution I thought it...
  31. mukul

    Black Body Radiation and ambient temperature

    Homework Statement In a dark room with ambient temperature T0, a black body is kept at a temperature T. Keeping the temperature of the black body constant (at T), sunrays are allowed to fall on the black body through a hole in the roof of the dark room. Assuming that there is no change in the...
  32. E

    Thermal expansion over a large temperature range

    So I've been working at a steel mill where we deal with billets cooling from temperatures around 1200 C to between 10-25 C. I have access to average thermal expansion coefficients over this temperature range. First question: Over a large temperature range as aforementioned am I correct in...
  33. M

    Converting Electromagnetic Energy To Temperature

    Homework Statement For a home work assignment, I have to build a theoretical device which uses a laser to boil water. But I have no idea how to figure out how long it would take the device to transfer enough heat to boil the water. The laser diode has a wavelength of 445nm. We are supposed to...
  34. RJLiberator

    PDE: Annulus question, Steady State Temperature

    Homework Statement Suppose the inner side of the annulus {(r,Φ): r_0 ≤ r ≤ 1} is insulated and the outer side is held at temperature u(1,0) = f(Φ). a) Find the steady-state temperature b) What is the solution if f(Φ) = 1+2sinΦ ? Homework EquationsThe Attempt at a Solution a) A =...
  35. lasisdabomb

    Calculate the Average Surface Temperature of Earth

    Homework Statement The Earth receives on average about 390 W m−2 of radiant thermal energy from the Sun, averaged over the whole of the Earth. It radiates an equal amount back into space, maintaining a thermal equilibrium that keeps the average temperature on Earth the same. Assuming the Earth...
  36. Minka Aduse-Poku

    Temperature Correction: Get Accurate Wall Surface Temperature

    Dear All, I have collected temperature data for a period of about 4 months with a device called ibutton attached to the surface of a concrete wall. My problem is the button is made of Stainless steel 305 and exposed to sunlight. I am interested in obtaining the wall surface temperature and at...
  37. y2j

    Automotive Temperature and mass flow rate of ICE exhaust gas

    Hi everyone I searched about the mass flow rates and temperatures of exhaust gases of light gasoline internal combustion engine at different condition but I don't fond anything yet . Anyone can guide me? .
  38. A

    Why boiling occurs at fix temperature?

    Can anyone explain to me why does temperature of water remains constant while boiling in an open vessel or in general sense why phase transition is isothermal in nature?please give me answers from thermodynamic point of view also.
  39. Elena14

    Temperature change in ice water interface

    A metal block at 500 K is kept on a large ice slab at 273 K.The metal block completely sinks inside the ice slab. I was told that the water in contact with ice would not change its temperature while the block sinks down and hence the "only" heat transfer from the metal block to ice slab will...
  40. A

    Calculating temperature rise due to solar insolation

    Homework Statement (This is not a homework problem, just something I'm curious about.) Assuming ideal conditions (clear skies, a flat landscape, no wind, anything else you can think of), is it possible to calculate how much the temperature (at 2 meters above the ground, as per meteorological...
  41. SpicyWassabi101

    Relationship between temperature and wavelength?

    Homework Statement A tuning fork with a frequency of 420 Hz emits sound with a wavelength of 0.82 m in air. If the temperature of the air increases, what will happen to the wavelength and why? Homework Equations The Attempt at a Solution I know temperature affects speed but I am not so sure...
  42. R

    Entropy of a Gas Under Pressure: Does Temperature Trump Pressure?

    Can anyone please answer this question? I have read that increased temperature increases entropy and increased pressure decreases entropy ,for a gas.And vice versa.decreased temperature decreases entropy and decreased pressure increases entropy.Can anyone please tell me for a gas under pressure...
  43. K

    Average height of molecules in a box as a function of temperature

    Homework Statement A circular cylinder of height H is filled with monatomic gas molecules at temperature T. The cylinder stands on the surface of the Earth so that the gas molecules are subject to the gravitational field g. (a) Find the average height, z , of the molecules in the cylinder as...
  44. yousaf nasir

    Combustion temperature and pressure

    hi i have a cylinder whose volume, intake and exhaust area is known. i know the amount of air entering into the combustion chamber(cylinder) and the amount of fuel entering into the combustion chamber. i am taking an ideal approach and assuming stoichiometric combustion (LPG). is there any...
  45. Searay330

    Finding temperature coefficient of resistivity of the alloy

    Suppose a wire made from an unknown alloy and having a temperature of 20.0°C carries a current of 0.529 A. At 52.4°C the current is 0.378 A for the same potential difference. Find the temperature coefficient of resistivity of the alloy. tempinital = 20C tempfinal = 52.4C currentInital = .529A...
  46. P

    How to find the temperature of the cold reservoir?

    Homework Statement Carnot engine A has an efficiency of 0.60, and Carnot engine B has an efficiency of 0.80. Both engines utilize the same hot reservoir, which has a temperature of 650 K and delivers 1200 J of heat to each engine. Find the magnitude of the work produced by each engine and the...
  47. P

    Density computation for high temperature, low pressure argon

    I am trying to compute the density of argon given the following conditions: T = 7000 K P = 21331 Pa For typical gases, I do not believe the ideal gas law would hold for such a high temp&low pressure regime, but since Argon is largely non-reactive, do you guys think using the ideal gas law would...
  48. Shackleford

    Derive differential equation that describes temperature

    I'm taking an engineering heat transfer course as an elective. 1. Homework Statement Copper tubing is joined to a solar collector plate of thickness t, and the working fluid maintains the temperature of the plate above the tubes at To. There is a uniform net radiation heat flux q”rad to the...
  49. C

    How can water be boiled without using heat?

    Hey everyone, I found this video on Youtube of this guy boiling water by reducing the pressure: I'm not sure how the gauge he's looking at works but I think this is the vacuum instrument he's using: https://us.vwr.com/store/catalog/product.jsp?product_id=4789427 ^It says that it provides...
  50. S

    Impact of container on final temperature of system

    Homework Statement A container contains a given mass of ice and a given mass of water both at 0 degrees Celsius. A given mass of aluminum is heated up to some temperature and submerged in the water-ice mixture. No heat enters or leaves the container. Given the specific heat of water and...
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