Temperature Definition and 1000 Threads

Hi everyone Would like some help here. If I draw a control volume across a valve that I can control the flow area to, and I know the temperature and pressure upstream of the valve, I will know its enthalpy:in. High temperature liquid going through this valve supposedly changes to steam due...

I'm a bit confused about the following situation. In a irreversible thermodynamics process the molar heat of an ideal gas changes according to a function of the temperature, say ##c_v=f(T)## (which also leads to ##c_p=R+f(T)##) and I'm asked to determine the heat exchanged during that process...

Hello everyone, I know that pre-main sequence stars do heat up because of gravitational contraction, and the increase in internal energy (and so in temperature) comes from this shrinking and is governed by the virial theorem (...

Homework Statement A cylindrical glass tube (linear thermal expansion coefficient ##\alpha##) contains liquid (volume thermal expansion coefficient ##\beta##). The height of the tube is ##h_{t,0}## and the height of the liquid inside of it is ##h_{l,0}##. If the temperature changes of an amount...

Hi! I am looking for a textbook that explains/describes for moving mechanical structures (such as linkage mechanism, engines, ... and not buildings, bridges, ...) the stresses, deformation, wear, temperature change, ... due to operating. E.g. Linkage mechanism: what are/defines the stresses...

Hi folks, Let's pick a simple example, the H atom. We can calculate all spherical armonics, all quantum numbers so we are able to know which are all the possible states of the electron. We know all the values this observables can take. But the question is, let's say we have a handbook of...

Homework Statement [/B] This is a practical problem, no homework question. I'd like to determine pressure (and O2 partial pressure) at altitude, yet following a more realistic real-world calc including measured data like relative humidity (RH) and temperature at that altitude, yet all I can...

Hi folks, so here's my recent problem, My car has a broken MAF (mass airflow sensor) the semiconductor innards are ok but the very thin metal strip that comes into the airflow tube has become brittle from old age and broken up. I know the MAF works when it sends a low voltage through the...

I'm doing independent study on semiconductors to prepare for a future class and I'm having problems with some problems that concern finding the n and p of doped Silicon given only a temperature, NA, ND, and Ni. I understand that n*p=Ni^2, but, given that this means that n does not equal ND (and...

Hi everybody! I´m chemist doing new materials and my understanding of physics is quite basic. I have a sample (single phase) of Ba and Ge and it shows diamagnetism in the magnetic susceptibility measurement, however it show a small temperature dependent behavior. As far as I understand...

Homework Statement Two scientists detected the cosmic microwave background radiation at a frequency of 160 GHz. What is the temperature of the universe? Homework Equations peak wavelength x temperature = 2.898 x 10^-3 c = f x wavelength The Attempt at a Solution I calculated the wavelength of...

Homework Statement Exercise 4 in the upload titled Dok1.pdf. Write down an expression for the canonical partition function for N ideal Na2 gas molecules, when the rotational contribution is treated classically, and all inner degrees of freedom are treated quantum mechanically. Use this and...

Homework Statement For a gas of N fermions with mass M in 2D in a region of area A in thermal equilibrium at temperature T, we are asked to find ##U/N## in fuction of ##T## and ##a=A/N##. The attempt at a solution I used ##U=\sum(<n_i>\epsilon_i) = \sum(\exp(\beta(\mu-\epsilon_i))\epsilon_i...

I mean, currently it seems that scientists are using equilibrium temperature of exoplanets (calculated assuming an Earth-like albedo) to determine whether a planet is habitable or not. But aren't there other more accurate ways to determine surface temperatures of exoplanets? I learned Wien's...

I am not a scientist or particularly good with math or formulas. I have been curious about this for a while, and would appreciate anyone clarifying/correcting me. I have a stainless steel container that can be heated up to 75 degrees celcius/165 degrees Fahrenheit in a bain marie. It can hold...

Hi all, Star surface temperature determines the occurrence of photosphere, where radiation can escape from star interior due to diminishing gas ionization and radiation absorption. If it was true the star photospheres should have the same temperature and Herzsprung-Russell diagram should be...

I'm putting together an idea about a weapon (insert hand-wavy science here) that fires extremely high temperatures a very short range (100 feet or so). A Heat Shotgun, if you will. The idea is that this weapon, with a single blast, could turn the majority of a human sized creature to literal...

Hello, A question I can't seem to find a simple answer to is, what happens to the Fermi-Dirac distribution at T grows large? Mathematics suggests that it approaches 1/2, like it does when the energy becomes equal to the Fermi energy. Or, are we not allowed to use the F-D distribution for high...

Homework Statement An extract form my textbook: " In general, easily liquefiable gases( ie. with higher critical temperature) are readily adsorbed as van der walls forces are stronger near the critical temperature. Hence 1g of activated charcoal adsorbs more SO2( Tc=630K),than CH4...

Homework Statement At low temperatures, the specific heats of metals is described by the expression ## c=kT + AT^3 ## , where k and A are constants. Here the first term describes the contribution of free electrons and the second the lattice contribution. How much heat is required to raise the...

Are the temperature over 24 hours normally distributed? Over 1 year? Over 15 years? Is there a difference in distribution depending on the time span Are MIN temperatures per day i.e. the coldest temperature measured over a 24hr period normally distributed? Over one month Over one year Over 15...

So say I have a PV-Thermal array and assuming standard test conditions. How would I calculate the temperature of the water coming out of the system? The thermal output of the system is 67.5kWp with a maximum flow rate of 65L/h. Approximately 500m of 3/4" pipes.

I'm doing some work on solar and I'm reading about properties of lamination materials, particularly EVA lamination. Anyway, one of it's properties is 'temperature stability' but I can't find a clear definition of what this means. EVA lamination is sandwiched in between a solar cell, so I can...

Since the temperature of a gas is related to its average molecular energy and the pressure to the average molecular momentum, it would seem that a Lorentz transformation would somehow relate the two. Does anyone know of related work?

can power supplies cause temperature fluctuations in a circuit? Or, instead, are they sensitive to temperature fluctuations in the environment, which can cause temperature fluctuations in a circuit?

Guys... If there is a bar, half of it is Copper and another half is Steel (Length wise) and both of its ends are at 1000K and I want to know how to find the temperature- length curve. this was an interview Question by the way.

Hello experts... I have an experiment pool boiling. The test section filled with DI water, and use thin flat copper as the heater that connected to the power supply. I want to ask how to measure or calculate the heater temperature if I only have the resistance, voltage and current data reading...

Consider the internal energy of a gas and solid (different materials) both at the same temperature, which material has the larger potential energy and why? Do they also both have the same kinetic energy? Finally is the definition of temperature as the average kinetic energy of the particles only...

Homework Statement [Update: just realized that the LMTD is a temperature difference, so my question was not valid] :P Calculate the logarithmic mean temperature difference (LMTD) to heat water flowing through a tube from 21 C (Ti) to 40 C (Te) if the tube has a fixed temperature of 45 C (Ts)...

on earth, we have the poles being very cold and mostly frozen, while the equator is very warm and humid. i would like to know specifically what causes this. i know it is partially because of their exposure to the sun, but i'd like to know some of the details and factors involved. i'd also like...

What happens to current in a solar cell when temperature increases? I found two sources with different information. 1) As solar panel temperature increases, its output current increases exponentially while the voltage output is reduced linearly.' 2) Whereas, this second website says short...

Hello, I am currently working on a project which involves compressing air at high pressures and temperatures. I spent hours having a look for a pressure and temperature dependent equation for the dynamic viscosity of air but the only ones I could find were all temperature dependent only, such...

1. Homework Statement Homework Equations KE = 3/2 R/NA T The Attempt at a Solution By using the formula above, I used 2.4 x 10^-14 J as the mean translational KE , but it should be 1.2x10^-14 , why? I thought the mixture contains both deuterium nucleus and the proton? Why half KE of mixture?

The index of refraction for a gas depends on temperature, as well as pressure. What is an experiment that would determine the temperature dependence of the index of refraction of air?

Homework Statement 5 g of water at 30°C and 5 g of ice at -20°C are mixed together in a calorimeter Find the final temperature of the mixture. Water equivalent of the calorimeter is negligible,specific heat of ice=0.5 cal/g°C and latent heat of ice =80 cal/g. Homework Equations...

Can the temperature of an object be derived from the EM Waves it emits? I know that everything having a temperature over absolute zero emits thermal radiations. The hotter the object gets, the higher the frequency of the wave goes. But for example if I have a hammer which emits a wave xHz...

After a cookout on Saturday, I left two cans of Coca-Cola in my bag. Around Monday morning which is almost two days later, when I left for school, the cans were still cold with moisture on it. The next day, I put another can of Coca-Cola in the car and only left it overnight to see what the...

Greetings, I get that increased temperature increases pressure. But does increased pressure increase temperature. For example: 1) If I press down on a table with a heavy object, does it increase its temperature. 2) Or does the pressure of the crust and the mantle of the Earth, contribute...

I am taking a protein supplement that has far too much sodium in it. If I took the amount I need every day, I would far surpass the safe upper limit of daily sodium intake. I had the idea of dissolving the pea protein powder in water, filtering out the sodium, and then evaporating the water...

I've been trying to wrap my head around the relationship between temperature increase of an object at a distance and temperature of a heat source. From what I've found, the temperature increase of an object from thermal radiation is affected by the inverse square law...

Hello all, I am working on a few test scripts to test the life of a hydraulic cylinder. (It is a mechanically operated cylinder and has a positive displacement) The testing will involve thousands of continuous pump and retraction operations, due to which the temperature of the piston seal and...

Homework Statement This isn't a specific problem, but my professor told us that we can calculate the size of a star if we know the temperature of it. Homework Equations Stefan-Boltzmann Law, Wien's displacement law. The Attempt at a Solution With the temperature i can also get the intensity...

Is there a formula or equation to find out how heated a place x meters/kilometers from a heat source will be, if we have the size of the heat source, it's shape, it's surface temperature, it's inner temperature, everything? + the distance between source of heat and the specific location is...

What determines the surface temperature inside a pot of boiling water, right over the heat source? Can it go much over boiling temp if the water's just gently boiling?

Homework Statement Homework Equations R2=R1(1+alpha(t2-t1)) The Attempt at a Solution R1=250/5=50ohms R2=250/3.91=63.94ohms R2=R1(1+alpha15degrees(t2-t1)) 63.94=50(1+1/254.5(t2-15)) t2= Now I found this online but the answers provided still don't match, 84.25 being the closest. When...

From what I know, temperature is defined to be the average kinetic energy of molecules within a system while heat is said to be the total kinetic energy of molecules. I know this might be something we can never achieve in real life but here's how my thought process went. Imagine you have a box...

The thermal efficiency of a reversible heat engine is solely a function of the temperature of the two reservoirs. η = f(θH,θC) = 1 - (QC/QH) (QC/QH) = 1 - f(θH,θC) (QC/QH) = Ψ(θH,θC) The simplest function that can be used is T1/T2 (QC/QH) = T1/T2 In order to define the Kelvin scale we assign a...

Homework Statement https://drive.google.com/file/d/0BxPEJS0qVOpeWENSREI1RlNsNDQ/view?usp=sharing A hub is connected to a shaft with a shrink fit (pressurized oil assembly, grease removed). The material of the hub is quenched and tempered steel (ReH = 450 N/mm2) and the material of the shaft...

I was reading this thread on Reddit about estimating drag using only a temperature profile. I was reading the responses, and I feel like most of them are missing something. Since this forum is more science-focused, what do you guys think...

Hi! These days I've been studying thermodynamics of quantum systems, and in so a very basic doubt come to me... I hope you guys can help me: When we study the usual hamiltonians of quantum mechanics (H-atom, harmonic oscillator, etc.)... Are these hamiltonians modeling the system at...