Thermal Definition and 1000 Threads

Guys, Maybe someone can help, as I am having a brain fart here trying to think of how this all works. Say for instance I have an electrical part that dissipates 10 W of power and I am removing this power through the use of a thermal strap to a heatsink. I think the...

Hi, :smile: I am learning about thermal physics and I have a doubt: Say that water and a box of wood, both with the same mass, are at 50 degrees Celsius. This does not mean that they have the same amount of energy (internal energy in this case?) right? That is because in water for...

Hi everyone. I am working to find out temperature distribution and thermal stresses in a structure. Can anyone please advice on which could be the best computational tool (ANSYS or ABAQUS or any other) for such kind of calculations. Thanks in advance.

Hello, I would like to compare rods made of different materials based on the amount of force or stress they would generate when fixed at both ends. normally, I would just compare the product of the coefficient of thermal expansion ( \Alpha ), change in temperature ( \Delta T ) and modulus (E)...

We know that youngs modulus(E) is stress/strain. In case of free body thermal expansion, if the material is allowed to expand and contract freely, than there are no stresses in the body. The body has only strains. That means the stresses are zero in case of free expansion. So in this case...

i have a question: In an Insulated Vesse, 250 g of ice at 0 degree Celsius is added to 600 g of water at 18 degree Celsius. Find: a) Final temperature of the system. B) How much ice remains. PLEASE POST THE WAY HOW TO DO THIS QUESTION :D

Hi to all Can some one help me for below question: What is different between "isotropic thermal conductivity" with " anisotropic thermal conductivity" ? where and when we must use isotropic or anisotropic ? which one is more accurate? I solve an example in a FEM software and it is...

Homework Statement A cylinder contains a mixture of helium and argon gas in equilibrium at a temperature of 121 C. Boltzmann’s constant is 1.38066 × 10−23 J/K, and Avogadro’s number is 6.02 × 1023 mol−1. What is the average kinetic energy of each type of molecule? Answer in units of J...

Homework Statement Homework Equations \alpha(T)dT = \frac{\partial L}{L} <--- Differential Equation given on formula sheet The Attempt at a Solution \alpha(T)dT = \frac{\partial L}{L} \int_{l_0}^{l_1} \frac{\partial L}{L} = \int_{T_0}^{T_1} \alpha(T)dT...

Hey, i just have a couple questions that need answers. Below I have a list of notes I have taken whilst researching how to analyze thermal and pressure stresses in a y bar exhaust. Things I need to design include the valve and the exhaust pipe itself. Am I missing anything to analyze? About...

For those of us trapped in a corner with difficult choices of whether to believe many worlds are splitted off billions of times every second or whether there is Godlike power to collapse the wave function in the universe or whether waves can travel forward or backward in time (Transactional) or...

Homework Statement Assume a two-energy-level system with energetic separation between the two levels of 10000 cm-1 (as you can easily see, λ = 1 μm equals 1/λ = 10000 cm-1, and E ∝ 1/λ, i.e. the unit [cm-1] defines an energy). a) What is the thermal population in the upper level? b) If you pump...

Good Day, I was wondering whether anyone has a reference or can point me in the right direction for a mathematical derivation of how the photons in blackbody radiation (for solids) are generated from thermal motion. Regards Max

Thermal Conductivity , k , for water is .1455 cal/sec/ meter * C ( converted watts to cal/sec) Q/t = k* A delta T/ d A= area M2 d = thickness of water/ice boundary layer Suppose I want to calculate time for 100 grams of ice to melt ( 8000 calories absorbed from surroundings by conduction. I...

Temperature describes thermal equilibirum. How?

Homework Statement [/b] E= 13600J, MAss of liquid = 0.1 kg, Temperature change = 25K 2. Homework Equations [/b] Pt/m*delta T The Attempt at a Solution what effect would doubling the time have on the specific heat capacity of the liquid? what i did was to say if the time is doubled...

I'm currently running RELAP5-3D to model a molten salt reactor and I require the thermal conductivity of graphite. Is there anyone that is aware of this value, or can inform me of a proper resource? Thanks!

0.03 kg of ice and 0.18kg of water are initially in equilibrium at 0 degree celcius in a container. Steam at 100 degree celcius is then passed by in until all the ice melted. The final temperature of the mixture as measured is 25 degree celcius. How much water is in the container in the final...

Homework Statement What are the factors that determines the thermal energy of a gas in a 3d object like a box Homework Equations The Attempt at a Solution I think thermal energy can be referred to as potential energy and also kinetic energy inside the box. If they are essentially...

Hi everyone. I want to find out thermal gradient (or temperature distribution) in a structure subjected to multiple mediums at different temperature. Would Ansys be the right tool for it, or can you suggest one? Would the methodology be to draft the structure in a simulation software first...

Hey, what are the most efficient/effective ways you know of to take thermal (heat) energy and convert it into either electricity or mechanical action in a portable form? I was thinking peltier devices, but turns out that only has an efficiency of about 10-20%. Steam power is another...

Hello All, I have to do a transient analysis of thin composite film. Following are the requirements: 1. Time t=0 to t=0.01, Initial condition of Temperature=300 K. 2. Time t=0.01 to t=0.05, Temperature=505 K. 3. Run the analysis from t=0.05 until a stable solution is obtained. I tried...

Homework Statement What is the indicated thermal efficiency of an engine? Fuel used in total 42.61 cc/min @ 1730 rpm. Fuel used to get to 1730 rpm = 29.16 cc/min no load. Fuel left = 13.45 cc/min to do approx 4.335 kw at 1730 rpm approx 40.95 kph Fuel heat content 34.8 kj/l...

Homework Statement A copper plate of length 1 m is riveted to two steel plates of same length and same cross-section area at 0°C. The tension (in kilo Newton) generated in copper plate when heated to 20°C is 56n. Find the value of n. (Given Ys,Yc,αs,αc,A) The Attempt at a Solution I...

We know that the particles in the hot universe obey Fermi/Bose statistics, but when we calculate the scalar dynamics i.e. in inflation or dark energy... and maybe also something else, it seems we don't take into account the statistics and just use one scalar field to calculate all these...

I'm not sure how to evaluate this integral. http://i111.photobucket.com/albums/n149/camarolt4z28/IMG_20110317_145314.jpg?t=1300391815 http://i111.photobucket.com/albums/n149/camarolt4z28/IMG_20110317_145259.jpg?t=1300391802

Hi If I have a gas of atoms that emit light, is it accurate to regard the gas as being a thermal source? Niles.

We have a customer asking us for the thermal conductivity of a product we sell. None of the engineers have that number. I can think of a simple experiment that might do it, but I don't know the math. I want to take a piece of this material (it's a pipe), put a cap on the bottom, then...

Does anyone have any good websites with practice problems and great in-depth explanations on thermal energy/heat transfer at the introductory level (grade 11)? I've searched many websites only to find questions that are too advanced. Questions like: What mass of steam is produced when 2.4 X 10^6...

Hi everybody, Homework Statement For one project, I need to find a material to control the heat transfer between two plates of aluminium by adding a plate or something in between. I'm so looking for a material which can help to reduce the heat transfer between the two plates (one about...

Hello my name is Colin Wilson and I am the inventor of a new mineral separation process. http://www.coldgold.rotoquad.com I am looking for help and/or a partnership in this endeavor. As a group I can not think of a better place to start. To test this new method of mineral recovery 3...

Homework Statement The rms speed of the molecules in 1.2 g of hydrogen gas is 1800 m/s. What is the thermal energy of the gas? Homework Equations m = Mass of 1 H molecule: 1.67 x 10^-27 kg N = Total # of molecules = 7.19 x 10^23 molecules c = rms speed The equation provided by my...

Homework Statement The door of an oven has a piece of glass of dimensions 20cm X 30 cm and thickness 0.50cm.when the interior of the oven is at temperature 200°C,determine the quantity of heat that flow through the glass in one hour.(for glass,K=0.80 Wm^-1K^-1) Homework Equations...

Homework Statement This is more of a concept that I am confused on. IF there are 2 metals, one on top of the other, and they are attached to each other and attached to a wall, and the only thing different between the two metals is the thermal expansion. When heated will the metal curve...

http://i111.photobucket.com/albums/n149/camarolt4z28/Untitled-1.png?t=1297136986 Huh? Its sum is 1.

This is a problem intended to show us that Astronomers are sometimes fooled into thinking that a cosmic source of radiation is thermal, when it is not. Here is the problem: Consider a cosmic source emitting one hundred solar luminosities all within 1 MHz of the single frequency of 22 GHz...

Hey everyone! Got an interesting problem here, I am thinking I did it correctly but I wanted to see your opinions. Here is the problem.. A 0.2-m-thick plane wall is constructed of concrete. At steady state, the energy transfer by conduction through the wall is 0.15 kW/m2. The inside...

This is my very first post... :) I found some help here: https://www.physicsforums.com/showthread.php?t=277092 But I have a difficulty in sloving second and third part Homework Statement The figure shows(check the link) a thermodynamic process followed by 1.90×10^−2 of hydrogen (link to...

A lead rod and a common glass rod both have the same length when at 21.0° C. The lead rod is heated to 50.0° C. To what temperature must the glass rod be heated so that they are again at the same length? I did this: L = a*L0*T a (thermal expansion) of lead = (29e-6) a (thermal expansion) of...

Hi, I have been looking at hoop stresses and the information I have found hasn't been all that useful to me as I am having a hard time converting the thermal contraction of a system into a pressure for the equation (stress=a+b/r^2). This is the thick walled hoop equation The disc is a few...

Homework Statement Ice has formed on a shallow pond, and a steady state has been reached, with the air above the ice at -9.6°C and the bottom of the pond at 5.5°C. If the total depth of ice + water is 2.1 m, how thick is the ice? (Assume that the thermal conductivities of ice and water are...

Homework Statement A solid cylinder of radius r1 = 2.5 cm, length h1 = 5.1 cm, emissivity 0.90, and temperature 28°C is suspended in an environment of temperature 46°C. (a) What is the cylinder's net thermal radiation transfer rate P1? (b) If the cylinder is stretched until its radius is r2...

Does anybody know? I tried googling can't seem to turn up any answers

Im working on test corrections that are due tomorrow, and I was out sick for around a month and a half or so. I have been trying to find these in our book, however, our book is pretty much a big hunk of annoying weight that should be used for a campfire. Anyway, I am looking for some help with...

Hello All, I have been trying to figure this out for quite some time now. Obviously, from a mechanical point of view, it is best to keep to keep the Playstation on a hard surface to ensure unrestricted air flow into the cooling intake vents. But, still remains, is a deeper question...

1. A mercury thermometer has a bulb of volume .100 cm^3 at 10degreesC. The capillary tube (initially empty) above the bulb has a cross-sectional area of .00012 cm^2. How much will the mercury rise when the temperature rises by 30degreesC? Ignore the thermal expansion of the glass bulb and tube...

Hi I am trying to solve this problem. I will present my solution though I couldn't get the tension right. At 40 Celsius , there is no tension in the wire. When the wires are cooled , they contract and the tension increases. But the tensile stress, which is force per unit area, will remain...

There seems to be considerable confusion in the scientific community about thermal energy and heat. I have read several textbooks on thermodynamics and several posts in scientific forums and they certainly don't agree on what is heat and thermal energy. For some: thermal energy is the kinetic...

Homework Statement Hi all I'm a little confused about work in gases. I thought I knew it now I'm not so sure. Basically I'm answering a question about work done on the gas in a reversible cycle where a change in temperature (T1 -T2)at constant volume (V1) is followed by a change in volume at...

Hello! I am wondering if anyone could recommend som literature for me to get my hands on. If there is any literature regarding how the appereance of a crack in a piece of thin metal (~0,4mm - 1mm) could be related to pressure fatigue or thermal fatigue. Does the crack due to thermal fatigue...