Thermal Definition and 1000 Threads

Homework Statement I'm having some trouble with this problem as it seems my concept of the problem is completely wrong. Could someone look through my solutions and point out what I understood wrongly? Thanks in advance. Homework EquationsThe Attempt at a Solution a) 21 macrostates - this...

Homework Statement Calculate the volume of 1.00 mol of liquid water at 20°C (at which its density is 998 kg>m3),and compare that with the volume occupied by 1.00 mol of water at the critical point, which is 56 * 10-6 m3. Water has a molar mass of 18.0 g>mol. Full answer please! Thanks...

Hello, I am reviewing some thermodynamics and heat engines. Heat engines are cyclical machines able to convert a portion (just a portion) of the thermal energy extracted from a hot reservoir into mechanical work. The residual thermal energy must dump into a lower temperature reservoir...

Homework Statement The question below is asking how long it would take for the cooler side of the handle to heat up till its unbearably hot. I'm having a bit of trouble trying to understand the solution and would like some guidance. I can't seem to get how the ##\Delta T ## that represents...

Homework Statement Question (b) (iii) Homework EquationsThe Attempt at a Solution The energy required to melt the ice is Q1=mL=3*0.025*3.3*10^5=24750J The energy released by water is Q2=mcT=0.33*4200*(22-T) Shall I calculate the energy that the ice needs after it melts into water? i.e...

Homework Statement Kerry is pulling a 156-kg sled along a snowy, horizontal path with a 620-N force directed at an angle of 29.0° above the ground. He pulls the sled over a distance of 26.0 m, and the coefficient of kinetic friction between the sled and the ground is 0.0622. I need to find the...

Homework Statement In the question, a person is pulling a 156 kg sled up a hill. A 620 N force is used to pull the sled up the hill that has an angle of 29° with the horizontal. The sled is pulled a distance of 26 m, and the kinetic friction coefficient is 0.0622. The system has been defined as...

Every objects emit thermal radiation. Now consider this case: Sun emits waves in a certian electromagneic spectrum (UV + thermal radiation + ecc...); glass is transparent to thermal radiation that usually reach Earth's surface. UV and other radiations are mainly absorbed by Ozone and other...

Homework Statement By means of a Maxwell relation derived from the Gibbs free energy and making use of the third law of thermodynamics, prove that the thermal expansion coefficient β must be zero at T = 0. I tried but I got something funny. Homework Equations $$G=U-TS+PV$$ $$dG=\mu...

By means of a Maxwell relation derived from the Gibbs free energy and making use of the third law of thermodynamics, prove that the thermal expansion coefficient β must be zero at T = 0. I tried but I got something funny. My working:

If two objects are at the same temperature, but thermally isolated from one another, are they still considered to be in thermal equilibrium with one another?

Hello, I am attempting to solve the 1 d heat equation using separation of variables. 1d heat equation: ##\frac{\partial T}{\partial t} = \alpha \frac{\partial^2 T}{\partial x^2}## I used the standard separation of variables to get a solution. Without including boundary conditions right now...

Homework Statement Homework Equations Thermodynamic Identity The Attempt at a Solution While I was able to work out the problem with the help of the hint, I couldn't completely understand the implication of said hint. The hint suggests that the equations for Chemical Potential in a process...

Homework Statement Homework Equations ##dS = \frac{1}{T} (dU - PdV)## assuming dN = 0 The Attempt at a Solution I have actually managed to solve all 4 parts correctly, except for the fact that I solved Part d) with the Sackur-Tetrode equation rather than the thermodynamic identity. I...

Homework Statement Homework EquationsThe Attempt at a Solution ## V(r) = \frac 1{r^3} \left( A - Br^2 \right )## At the bottom of the well, r is verry small. So, ## V(r) = \frac A{r^3}## Assuming the validation of Equipartition of energy theorem, since the degrees of freedom is 1, the...

I took Stephan's law for thermal radiation and I have a couple of questions about it. 1) The law states that the full energy radiated in 1 sec is equal to c T^4 where c is 5.67*10^-8 and T in kelvins and In the book they said if it has surroundings then the net energy emitted would be q = c A...

Homework Statement Hi there, I am designing a heat exchanger and I am really struggling to find out how to fairly accurately estimate the density, viscosity and thermal conductivity of a gaseous mixture at ~~20bar. There is 8 components in the mixture: methane, ethane, ethene, ethlyene oxide...

Problem Description: I have a solar panel of some surface area, material, and thickness mounted to an enclosure. The panel is isolated from the enclosure at some distance with a multitude of materials (air, insulation, plastic, metal) between the back surface of the panel and interior volume...

Question#1 I would like to compare a 100' length of 4" PVC pipe with air in it surrounded by Earth and/or water. What length of 4" copper pipe would equal a 100' length of PVC? Question#2 If the inside of the pipe had turbulence what length of non-turbulent 100' PVC 4" pipe would it equal? I...

Homework Statement A metal rod of length length L, linear coefficient of expansion a, is fixed at both ends to the walls. When the temperature is increased byΔT, the rod bends into a circular arc due to thermal expansion. 2 Relevant equations a)Find the radius of curvature R of the rod by...

I am trying to calculate how much a foil liner helps keep the inside of a package cool. I have calculated the rate of conduction but am now concerned with radiation. Above is the equation I am using. The emissivity for the material is 0.05, the area is 1 m^2, the outside air temp is 295...

HI, I have application where i need to lift metal plate, 3kg weight, ( 3mmX 15mm), 250degree.C hot, for the period of 1min and put it back. For lifting purpose i am using actuators. As i have no opportunity to make hole in plate i have to use magnet for lifting purpose. I got Electromagnet...

Homework Statement Homework Equations dQ/dt = -kA(dT/dx) The Attempt at a Solution I tried to use Fourier's law of Conduction on this one. I subbed dT for (Θ0 - Θ1), and l(t) (function for thickness of ice against time) for dx, reason being that the sheet of ice should get thicker. I then...

Homework Statement Homework EquationsThe Attempt at a Solution Part 1.1) I managed to find the energy needed to melt the ice, before using ΔU = Nf½KΔT to solve for the new temperature, which was correct Part 1.2) Initially tried using ΔQ = mcΔT before realising that I didn't have the mass...

Back in... man... probably 1996 I went to work with a thermal tumbler filled with some hot beverage or another. I settled in and took a swig; the liquid was good and hot and I kind of marveled at how well the tumbler worked and how it was nice to have a warm drink in my cool environment and...

Hi, Can someone start me out with creating predictable temperatures and inputs for calculations. Here is a miniature example of the type of parabolic circulated water heating devices I have been building. My first questions would be what is the potential heating energy of the sun per cm2? And...

Hello! Hopefully someone here can help with this problem: I have a condenser that holds 35 gallons of water to cool the copper coil on my still. I need to know if I can create a closed loop system of cooling water that allows me to avoid running a chiller. I know that there is probably an...

Since thermal energy is the vibration of molecules and sound is too, what is the difference? And why exactly do atoms radiate different energies as a result of vibrations?

In thermal imager vs IR spectroscopy, they both look at the IR radiation of an object. What is the difference between the two.. I know IR spectroscopy look at the dipole moments of molecules. But in thermal imager.. do they also image the dipole moments of molecules? Also why you see images in...

Homework Statement A hollow aluminum cylinder with a depth of 20.0 cm has an internal capacity of 2.000 L at 20.0 C. It's full with mineral turpentine, at 20.0 C. The two of them are heated slowly, until the temperature reaches 80.0 C. a) How much of the mineral is spilled outside the...

Is a "fast" reactor more economical in terms of capital investment than a thermal one? I am asking this because I assume a fast reactor only needs a smaller startup U235 source of on average 20% enrichment but can later run on its own produced fissile material and would normally for the rest of...

Does the phonon thermal conductivity account for a large part of the total thermal conductivity in thermoelectric materials like Bismuth Telluride? As far as I know, the phonon conductivity is the largest contributor to the total thermal conductivity in semiconductors. Is this still true for...

Homework Statement for number 3,4,5 I'm still tryingHomework Equations PV/T = PV/T q = ΔU + W W = P ΔV The Attempt at a Solution (3) I used PV/T = PV/T to find the ΔT for each process for A→B I find PV/TA = P3V/TB ----- TB = 3TA (T increase) for B→C I find P3V/TB = 4P3V/TC ----- TC =...

Okay, I will give a quick run down of what I am trying to do here. What I want to do is build a tesla turbine from old hard drive disks. Being that they're already rated for high RPM, it seems like a viable option. Now these disks are probably going to be aluminum and I am probably going to buy...

Say you have an object with a negative heat capacity. This means that the object increases in temperature as it radiates energy and decreases in temperature as it absorbs energy. I don't understand why this object cannot be in thermal equilbrium with a reservoir. Any help would be greatly...

Hi guys, From Boyles Law, we know that Volume is inversely proportional to Pressure give that the temperature is kept. My question, if we decrease the volume, the pressure will increase due to rate of change of momentum ( we can say those two are proportional), then why can we not claim that...

Homework Statement A satellite to reflect radar is a 3.5-m-diameter, 2.0-mm-thick spherical copper shell. While orbiting the earth, the satellite absorbs sunlight and is warmed to 50 °C. When it passes into the Earth's shadow, the satellite radiates energy to deep space. You can assume a...

Homework Statement A one-liter pot is completely filled with oil. Heat is applied to the pot&oil and the temperature rises from 15°C to 190°C. How much oil is spilled over? The linear coefficient of thermal expansion for oil is 0.68*10-3; the one for the pot is 2.4*10-5 Homework Equations...

Hello all, I am a third year physics and math major at a quarter system public school. This year I've been getting pretty decent grades and achieved a 4.0 last quarter on 4 upper div math and physics classes. This quarter I am taking Topology II, EM Waves, Thermal Physics and a breadth class...

I haven't been able to find much information on the thermal decomposition of metal oxides into their corresponding metals and oxygen. What temperature would Fe3O4 decompose mostly(80%) into its base elements? Additionally, how can this information be determined based upon bond...

Hi, I am trying to work out how much each dimension of a solid (for instance an annular disc) made out of steel changes assuming that the solid is heated uniformly and is not constrained at any of its boundaries. Am I right in saying that, the linear expansion equation L = L_0 (1+ α ΔT) can be...

Homework Statement The 40 ft long A-36 steel rails on a train track are laid with a small gap between them to allow for thermal expansion. Determine the required gap in inches so that the rails just touch one another when the temperature is increased from -20 F to 90 F. The cross sectional...

I'm (self)studying the physics of heat transfer at the moment. My book gives a relationship between heat transfer rate and thermal resistance as ##\phi=\frac {A \Delta T} {R}##. My book is not in English, so hopefully that is not the cause of this misunderstanding. I double checked that heat...

More thermal conductivity means there's more energy?...

Is it true for all material that if young's modulus is high then melting point will be high and coeff of thermal expansion will be lower? Any example that doesn't follow the above statement. Many Thanks

Homework Statement 2. Homework Equations are given in the above picture 3. The attempt at the solution In part a) I simply rearranged the other expressions given and subbed them into the relationship for relative velocity and came out with Vns= Qdot/ρsT(1- ρn/ρs).Then in part b) I started by...

https://en.wikipedia.org/wiki/Future_of_an_expanding_universe "Over an infinite time there could be a spontaneous entropy decrease, by a Poincaré recurrence or through thermal fluctuations (see also fluctuation theorem)"

Title says it all. Made a few google searches and couldn't find any information. Is there a reason why it is so large, or is it just a coincidence of nature?

There's something that has been bugging me for over a year now and I seem to be unable to find the answer. I would appreciate it very much if somebody could help me out. The thing is that I don't understand how it is possible that in second order phase transitions the correlation legth becomes...

I have a question about thermal expansion of liquid into a gas void. Imagine a closed upright cylinder filled mostly with water – say 99%, and the remaining 1% is gas. Now imagine that you heat the cylinder and its contents. The water will expand by ΔV owing to thermal expansion. The gas...