Temperature Definition and 1000 Threads

The understanding that I have of temperature is that it is defined as the vibration of particles. Now, does this mean that in a vacuum where there are no particles the temperature is the absolute 0 ?

Homework Statement Show that the temperature of non-relativistic matter scales as ##a^{-2}## in the absence of interactions. Start from the zero-order part of Eq. (4.68) and assume a form ##f_{dm} \propto e^{-E/T}=e^{-p^2/2mT}##. Note that his argument does not apply to electrons and protons...

Hi all, In S. Weinberg's book "Cosmology", there is a derivation of the slightly modified temperature of the cosmic microwave background as seen from the Earth moving w.r.t. a frame at rest in the CMB. On Page 131 (1st printing), an approximation (Formula 2.4.7) is given in terms of Legendre...

Hi! Here's a tricky thermodynamics problem, I hope you can help with it. 1. Homework Statement The boundary between two different materials can be divided into two different kind of phases: bulk phases and surface phases. For example, let's consider a boundary between water and air. We can...

Why laser output power decreases with increasing temperature? By increasing temperature, I mean increasing temperature of the active medium. I think that thermal lensing alone should not have effect on output power? Just different focusing (focal length). What happens with energy levels in...

Hi! My question is: I understand that at noon-day it’s hotter because of the angle with which sun rays enter our atmosphere. But at the same time, I was wondering that the band of radiation responsible for heating things is infrared, and that at noon basically all bands of lower frequency than...

How to get to the expression for equilibrium recombination temperature for Helium?

Homework Statement I have a copper tube with outer radius r2 and inner radius of r1. Half the tube is exposed to the surrounding air while the other half is embedded into the ground. The outside air temperature is T2 and the ground temperature is T3. What is the air temperature inside the tube...

I am trying to find the thermal speed of electron at room temperature. kT = (1/2)mv^2 which gives v=√((2kT)/m) but answer says it should be √((kT)/m) Where did that 2 go?

Salutations, I'm starting in statistical mechanics and reviewing some related studying cases I would like to understand what occurs in small systems with normal modes of vibration, for example, a small system that has 2 normal modes of vibration, with natural frequencies $$\omega_1$$ and...

Homework Statement Two blocks of iron, one of mass m at 10.0C and the other of mass 2m at 25.0c, are placed in contact with each other. If no heat is exchanged with the surroundings, which of the following is the final temperature of the two blocks? A)10 B)15 . D) 20C ( this is the answer) The...

Homework Statement Star 1 emits energy at a rate that is 2 times that of Star 2. If Star 1 also has a radius that is 3 times larger than Star 2, how do the temperatures of the stars compare? a. Star 1's temperature is 2.58 that of Star 2. b. Star 1's temperature is 3.75 that of Star 2. c...

What is the difference in temperature with different thermometers for the same object? Thanks !

Hello, Can someone please tell me what the mean rating temperature in the tables provided in ASHRAE fundamentals, ASHRAE standard 90.1&90.2 for chilled water insulation indicates.

Homework Statement Helium is kept in a pressure vessel at a pressure of 5.42 bar and the resulting density is 0.92 kg/m3. The gas constant R is 8.314 J/(mol*K). The volume of the vessel is 1589.194 m3. I need to find the temperature of helium in Celsius. Homework Equations...

I was thinking about the fact that space contains all sorts of matter and that these objects have temperatures. But then I read that space itself has a temperature depending on where you are. The cosmic background radiation for example has a temperature of 2.7K. Can someone explain what that...

Knowing the following information: Sun surface temperature of 5788 K, Sun's core is between 20-25% of radius. I tried to (perhaps naively) calculate the temperature to the edge of its core from the surface temperature, using an inverse square law. Depending on which value you use for the core...

Homework Statement Compute the specific heat of black hole Homework Equations ##T=\frac{2}{r_+}-3/2048 r_+^2-\frac{6r_+^3M^2}{(M+r_+^6)^2}## ##f(r)=1-\Big (\frac{r^2}{64}+\frac{Mr^4}{M+r^6} \Big ) ^{1/2}## ##r_+## is the horizon where ##f(r=r_+)=0##. The Attempt at a Solution I tried to...

Homework Statement I have had a question in my quiz that I don’t remember very well, but here’s a diagram and there’s no need for numbers in axis because it’s a concept- based question with no calculations. The question asks if an ideal gas system moved from A-B-C-A. Where is the process by...

Hi, For an ideal Rankine cycle, the temperature-specific entropy diagram can be given as follows, The pump in this cycle is isentropically 100% efficient. My question is that why the temperature of the water increases as it flows through the pump (point 1 to 2) if the pump is 100%...

Homework Statement A gas-fired tube heater has the following data: Dimensions of the combustion chamber: 15 * 20 * 40 ft Tube outside diameter: 5 in Temperature of the tube=800° F Center to center spacing: 8 in Number of tubes (arranged in a single row of which 6 tubes are shield tubes) ...

I heated two different materials with a laser beam for about 10 seconds and these are the measured temperature profiles: From the various solutions to the general heat conduction equation, temperature rise seems to increase with increasing thermal resistance of the material. The total...

Homework Statement A black and yellow body at room temperature are thrown into a furnace at very high temperature. How will the initial and final brightness of both compare? Homework Equations λT=constant The Attempt at a Solution The rise in the black body's temperature will be higher...

Homework Statement What would be the increment in heat energy radiated when the temperature of a hot body is raised by 5%? Homework Equations P=σεAT^4 The Attempt at a Solution dP/P=4dT/T dT=5 when T is 100 initially. Let's assume P was also 100 initially for convenience, therefore dP should...

Homework Statement A piece of metal is heated by supplying a constant power P. The temperature of the metal starts varying as T=kt. The heat capacity of the metal as a function of temperature is? Homework Equations Q=CdT The Attempt at a Solution From Q=CdT, dT is k, since P is Q/t, I plugged...

Homework Statement Consider the following reaction. 2 HCl(aq) + Ba(OH)2(aq) BaCl2(aq) + 2 H2O(l) ΔH = -118 kJ Calculate the heat when 100.8 mL of 0.500 M HCl is mixed with 300.0 mL of 0.450 M Ba(OH)2. Assuming that the temperature of both solutions was initially 25.0°C and that the final...

Homework Statement Consider the dissolution of CaCl2. CaCl2(s) Ca2+(aq) + 2 Cl-(aq) ΔH = -81.5 kJ A 10.6-g sample of CaCl2 is dissolved in 109 g of water, with both substances at 25.0°C. Calculate the final temperature of the solution assuming no heat lost to the surroundings and assuming...

Generally, a material is metal or insulator is simply determined by the gap. But if we view it in another way, to measure the resistance in different direction, says x and y, and there are usually different. And then measure the resistance change with temperature. Usually, the resistances goes...

When I use the air conditioner in my Toyota Camry, and I move the temperature control towards warmer: Does it make the AC cycle on/off thus saving fuel? Does it mix warm air with the cold, thus saving no fuel? I couldn't find an answer to this on Toyota forums.

DiNitrogen is very unreactive due to the tripple bond it has, but what happens if it heated to very high temperature and bonds are broken? does it start behaving as a strong oxidiser. I could not find iinformation on at which temperature this happens but let's assume 3500K in a Tunston reactor...

Hello all It's been a while ,as I read the almost daily news on climate change , some question come up to my mind , dose the ionosphere has any effect on climate change , as we all know now the Earth magnetic field is weakening ,and the temperature is rising ,dose this two variables related to...

Hi guys, I am currently working through a book about thermodynamics and statistical mechanics as I was not so great in these course during my undergrad studies. First question: The book introduces heat as the kind of energy that terminates the temperature of a system. In other words: Give heat...

*Given Newton's Cooling formula, where T(t) predicts temperature, and where Te is the temperature of the enviornment, T[0] is the temperature when t = 0: T(t) = Te + (T[0]+Te)e^-rt predict Te when T(120)= 86.632 T(240) = 79.210 r = 0.001 I don't know how to even remotely go about solving...

Hi Everyone! There is a type of CO2 laser cutter power meter on the market (Product link removed) The meter uses a block of black anodized aluminum bonded to the end of basically a mechanical meat thermometer, and has a zero adjustment on the back of the face to set the base temperature to...

Homework Statement This is the problem. A pair of eyeglass frames is made of epoxy plastic. At room temperature (20.0°C), the frames have circular lens holes 2.20 cm in radius. To what temperature must the frames be heated if lenses 2.21 cm in radius are to be inserted in them? The average...

Homework Statement A glass bottle of nominal capacity 250 cm3 is filled brim full of water at 20oC. If the bottle and content are heated to 50oC, how much water spills over? (For water, β=0.21X10-3 K-1. Assume that the expansion of the glass is negligible.) Homework Equations (dv/dT)/v =...

Q7, b is where I got stuck

I am looking for an explicit equation that shows that a sample with lesser volume will reach higher temperatures when irradiated than a sample with a larger volume. The samples in my project are biological tissues which are being irradiated by a laser. In my experiment, using a thermal camera I...

Homework Statement Convert 62.0 °C to Fahrenheit Homework Equations °F=1.8(°C) +32 The Attempt at a Solution °F=1.8(62.0) + 32 = 143.60 I am confused on the significant figures for the answer. Does the temperature equal 143.6°F because 32 is an exact number? Or 144°F because 32 is not...

Hi, I have a hypothetical question: We have a fan which has no internal dissipation - electrical or mechanical. The fan is made to run in an adiabatically sealed room. The internal energy of the air in the room increases due to work input. This work input increases the temperature and...

Hi, I am trying to figure out whether there is a way to express the ratio of the critical current of a superconductor at zero and finite magnetic fields [denoted as Ic(0) and Ic(B)] as a function of the ratio of corresponding critical temperatures [denoted as Tc(0) and Tc(B)]. According to...

Hi, We know that a heat engine working on a Carnot Cycle the efficiency is: 1 - QL/QH = 1 - TL/TH where T is in Kelvin. But if we use a different absolute temperature scale whose values at TH and TL are different, then the value of efficiency also changes. I am confused about this issue...

Homework Statement [/B] Strap in, this one's kind of long. (This problem is from 'Six Ideas That Shaped Physics, Unit T' by Thomas A Moore, 2nd edition. Problem T6R2.) Imagine that aliens deliver into your hands two identical objects made of substances whose multiplicities increase linearly...

I'm working on a DIY EFI system for automotive use. I have a question about the mass air flow sensor operation. I know they measure the volume of air passing thru them. But the question is whether that measurement needs to be corrected for air temperature or if the MAF sensor does that by...

This question is more for practicality than anything else, and I realize it may be partly subjective. At what temperatures can the 273 degree difference between Kelvin and Celsius scales be ignored? I'm thinking for examples regarding stars and very high temperatures. Surely once you get to 15...

Homework Statement An inflated tyre suddenly bursts. As a result of this the temperature of air (a)increases (b) decreases (c) may increase or decrease (d) remains constant. Homework EquationsThe Attempt at a Solution The answer in the book is (D) remain constant. Does it mean air outside the...

I think the title sums up pretty well my doubts. I learned QFT from Peskin and Schroeder and other common sources, all implicitly defined QFT at zero temperature. Then I started learning about lattice QCD, how to define the action, how to find continuum limits, the importance of the dependence...

What is the difference between a red object at room temperature and a heated red object (Metal for example). They are both red except one is cooler then the other? Why aren't the red objects in my room not hot like the heating of a metal?

Hi; Let's imagine that I have an antenna and a biological tissue. The antenna emits the frequency of 1e7 Hz and I have a temperature increase x. When the antenna emits the frequency of 3e7 and 6e7 Hz the temperature increase is the same. How can I explain?

In bolometers, incoming radiation warms a strip of material. this material will have a large thermal coefficient of resistance, leading to a (small) resistance change in the material. the inventor, Samuel Pierpoint Langley apparently used this to detect a cow from 1/4 of a mile away using a...