Temperature Definition and 1000 Threads

Homework Statement Consider a one-dimensional metal wire with one free electron per atom and an atomic spacing of ##d##. Calculate the Fermi temperature. Homework Equations Energy of a particle in a box of length ##L##: ##E_n = \frac{\pi^2 \hbar^2}{2 m L^2} n^2## 1D density of states...

Hi, As some of you may know, the temperature profile inside a pellet is determined by using the equation given below, Tx=TRim+ρ(rpellet2-x2)(4Kf)-1 Where; ρ is power density. Kf is thermal conductivity. The temperature profile is strictly dependent on the material used as a fuel. The...

According to the Unruh effect an observer who is has an acceleration ##g## will observe the temperature of the vacuum to be $$T=\frac{\hbar g}{2 \pi c k_B}.$$ According to the equivalence principle the observer should measure the same Unruh temperature if he is sitting on a planet whose surface...

Homework Statement How much heat in joules is needed to raise the temperature of 7.0 L of water from 0°C to 78.0°C? (Hint: Recall the original definition of the liter.) Homework Equations How much heat in joules is needed to raise the temperature of 7.5 L of water from 0°C to 87.0°C? (Hint...

Greetings I am asking about the reliability of using a thermal gun to check if there is passing downstream the valve. The fluid is either steam or air. Wouldn’t the pressure and temperature drop sharply downstream the valve if it is closed but passing ? again I am talking about air or steam...

Hi, I have a little conceptual question. I have an idea about the topic, but I would need to formalize it a little bit. The problem is the following: Imagine the following scenario: You put a little bit of water in a bottle, you assure yourself that everything as at a constant temperature and...

Homework Statement Hi Physicsforum, this is my first post so apology if I make unclear equation. I try to solve this question by pluging t0 as temp. at Valley and t as temp. at Antartitca directly as oppose to setting separate equation. I got different answer than the solution said While...

Why can sometimes entropy remain constant with increase of temperature and vice versa?Entropy implies transfer of heat and heat must increase with temperature.I am unable to intuitively understand.

Hello all, It seems like a fairly straightforward question but I cannot find any information in the literature. Let's suppose we apply a crack driving force K1=45 MPa.m^0.5 to a notched specimen with an upper shelf fracture toughness K_mat = 50 MPa.m^0.5 at room temperature T0=20 oC. Under a...

Does anyone know of any material that's not as brittle as ceramic that can withstand high temperatures and is non-conductive? I'm talking abou a max temp of 800degC of heat radiating from a hot steel coil. Components will be inside of the coil for a short period of time but trying to prepare...

Homework Statement Homework Equations The Attempt at a Solution I am having problems with all parts of this problem, but I'll start with part A. Comparing the 2 equations I see that Ca could be 3/2 based off the hint, but I am not sure why or how it would be 3/2 or -3/2. The problem...

Hi, I'm hoping someone can point me in the right direction please. I'm using the Planck 2015 CMB temperature (intensity) SMICA pipeline maps (Nside = 2048) and am trying to determine the temperature variance of each individual pixel. Variance and hit-count were provided with the 2013 CMB maps...

I'm reading a book on thermal physics and the author says this: "In general, the internal energy will be a function of temperature and volume, so that we can write U =U(T,V) " How do we know this intuitively and how do we know that internal energy is not a function of pressure as well?

The attached Image is a for some kind of heat map of temperature with the y-axis corresponding to the time of day and the x-axis corresponding to the time of year. It was generated in Excel from weather data files. What is this type of data representation called? I've seen the same type of...

Homework Statement a) A mass of 0.12 kg of air has an initial temperature of 500°C and pressure 0.8 MPa. If the air is expanded according to the law pV1.2 = c to a final volume of 90 litres, determine i) its initial volume, ii) its final pressure, iii) its final temperature...

Homework Statement How to find mass of one of the two liquids being mixed if we know all other variables in this formula T = ( m1c1T1 + m2c2T2 ) / ( m1c1 + m2c2 ) ? Homework Equations T = ( m1c1T1 + m2c2T2 ) / ( m1c1 + m2c2 ) The Attempt at a Solution

Homework Statement A liquid A initially at temperature T1= 28.4°C, is heated by an immersion heater in container. The resulting temperature T2 is recorded at 1 minute intervals and the following results obtained. (I will post a picture) (a) Complete the table by computing temperature changes...

Homework Statement We consider a planet in a circular orbit around a star. I have to calculate the average temperature knowing that the radius of the orbit is 0.4 AU and that the planet reflects 30% of the incident light Homework EquationsThe Attempt at a Solution I used this equation F = L/4...

There are 2 types of temp rise measurement for electrical devices, 1)resistance type 2) thermocouple type (direct measurement) My query is 1) which method is superior and please explain me the reason. 2) Which gives higher value of measurement? Thanks in advance.

I'm currently trying to find how much water can be condensed from an airmass of a certain dewpoint if it is sent to a lower temperature. The water will be condensed over a period of time. I have the dewpoint of the initial air and the temperature of the environment where the moist air is being...

I'm just a layman here, who enjoys science and astronomy. I was reading about the temperatures of the cores of black holes being extremely cold, and how time at the singularity...progresses super, super slowly. But this is only as measured from an outside observer's perspective (such as from a...

For the material used in a heater plate to generate heat for example, for a given amount of power (say 4.5 kw) does the higher resistance of the material mean it will produce a higher temperature? Or is it the other way around?

I've read that there is a lowest temperature which is absolute zero where nothing happens, i.e. no vibrational activity from atoms. Is there also a highest temperature, i.e. an absolute max temperature?

Hi, in determining the temperature of stars using colour index (U-B,B-V,V-R, etc), why do we need to use the appropriate pairs of filters based on their range of temperature? (this is what i read from wiki) For cool stars, we use R-I, and for hotter stars, we use B-V. I don't understand how...

i have an equation like this: Given m(B-V)= 1.2 +- 0.2 How do you calculate the uncertainty in T? (btw, I solve T using graphs by finding the intersection point) My idea was first to calculate T when m(B-V) =0.2, and I then calculate T when m(B-V)= 1.2 + 0.2(its uncertainty). and then find the...

Homework Statement A 3-ft^3 container is filled with 2-lbm of oxygen at a pressure of 80 psia. What is the temperature of the oxygen?Homework Equations pV= nRT T= PV/nR R= 10.7316 psia x ft^3/ lbmol x R The Attempt at a Solution Hi everyone! So I understand how to use the Ideal Gas Law but my...

Hi, I'm trying to find temperature of stars using the stars' B-V magnitude by using the Planck law. However i do not know how to solve for T (assume other quantities are all given and determined first). Any idea how to do so? I already tried to do it but reach a dead end. Here I attached the...

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...

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...

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...

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...

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...

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...

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...

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...

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

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...

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

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...

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...

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?

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!

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...

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...

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

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...

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...

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...

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...

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...