What is Thermal: Definition and 1000 Discussions

A thermal column (or thermal) is a column of rising air in the lower altitudes of Earth's atmosphere, a form of atmospheric updraft. Thermals are created by the uneven heating of Earth's surface from solar radiation, and are an example of convection, specifically atmospheric convection. The Sun warms the ground, which in turn warms the air directly above it. A thermal is a rising mass of buoyant air, a convective current in the atmosphere, that transfers heat energy vertically.

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  1. S

    Steady State Thermal Analysis - Simulation

    I am simulating a hot forging process in LS-Dyna. A tool is contacting a hot workpiece for 2 sec every 10 sec (--0 sec--contact--2 sec--no contact---10 sec--) in a factory. Since this is a continuous process, the tool should, at some point, attain steady temperature. I have tried to recreate it...
  2. Rob B

    Shear stress damage due to thermal gradient

    I'm trying to use my rudimentary understanding of material physics to understand a simple problem, and am getting stuck - I hope you can help! My idealized case involves a sheet of infinite extent in length and width direction, to which a linear thermal gradient in the depth dimension is...
  3. warhammer

    Mean Free Path (Introductory Thermal Physics)

    We have the area of incandescence. Using that we can find the radius and subsequently the diameter. A=π* r^2 -----> r= 0.0025m so d=0.005m Using the formula (given by Clausius as we are not specified in question whether it's a Maxwellian distribution or not) Mean Free Path λ=...
  4. warhammer

    Question in Thermal Physics (Van der Waals' Equation)

    <Using the hint, I tried to find the van der Waal constants in molar form. Since STP is mentioned, I used the unitary method relationship- 22.4 L=22400cm^3=1 molar V <To find a possible conversion standard between cm^3 and mol; which turned out to be 1cm^3= 4.46*10^-5 mol. <Then I used the...
  5. KyleGranger

    Basic MOSFET Thermal Design: Parameter Calculations from Datasheet

    I would like to be able to determine the current through a device for a given junction temperature. I am looking at a datasheet and notice that it gives the device power dissipation with different case temperatures. Since the maximum junction temperature is 175 C, I believe that means that lower...
  6. K

    A Thermal shock wave question from my hydrodynamics simulation

    This is a fluid dynamic simulation. The top area has 100 degrees Celsius. The bottom area has 0 degrees Celsius. And both are filled with an ideal gas which is 1-atmosphere pressure. Two areas are connected through the left small line. Another part is blocked. So heat transfer can only happen...
  7. bob012345

    A Rippling Graphene Harvests Thermal Energy?

    It is claimed 2D Graphene sheets can be used to harvest thermal energy while being at the same temperature as the surroundings in seeming contradiction to Feynman's *argument (in the popular accounts). However, the academic papers referenced below make the claim everything is well within known...
  8. S

    Calculating Effective Coefficient of Thermal Conductivity

    I know k is thermal conductivity but my teacher never told me about effective coefficient of thermal conductivity. I tried googling and found: $$k_{effective}=\frac{\Sigma{k.A}}{\Sigma A}$$ But I don't know the area to used that information. Is there another approach to do this question? Thanks
  9. SilverSoldier

    Thermal Expansion of a Triangular Frame

    Suppose each side has initial length ##l##. The solution taught to me is as follows. Considering the lengths of the rods after expansion, we write $$\dfrac{3l^2}{4}\left(1+\mu\theta\right)^2+\dfrac{l^2}{4}\left(1+\alpha\theta\right)^2=l^2\left(1+\lambda\theta\right)^2$$ according to the...
  10. S

    Thermal Physics: Computer cooling

    Hello folks, I have a bit of a time sensitive question, if anyone happens to read this soon. A computer box consumes 80W power constantly. Outside temperature T= 290 Kelvin. Ambient pressure 10^5. If all the heat generated is expelled at 5 litres per second, estimate the inside...
  11. D

    PEX Pipe in Residential Subfloor Thermal Mass

    Hello friends! We are installing a future provision for a Rocket Mass-type woodstove in our home. This is a future project but realized that we could take advantage of the open area between the footing and finished floor by adding an insulated block of concrete with PEX pipes for Heating and...
  12. J

    Relationship of Modulus to thermal expansion

    I'm trying to figure out how to relate expected thermal expansion of a uv cured polymer within a rigid cylinder to a modulus specification. The issue is the expected change in refractive index due to thermal expansion. The expansion coefficients are not available. Anybody have an idea. Do...
  13. M

    Thermal time scale in tubular flow reactors

    So if I have a tubular reactor for nanoparticle synthesis (PTFE tubes ID:2mm). The tubes are heated in a furnace. liquid Reagents at room temperature are pumped by a syringe pump and directed toward the furnace. The reagents decompose to form nanoparticles once they reach the steady-state...
  14. E

    Thermal energy transport via conduction

  15. Rlwe

    Thin disc with high thermal conductivity

    I've tried to explicitly solve the Fourier's equation in cylindrical coordinates but I'm getting some messy integrals which cannot be solved analytically. Additionally my instructor said that there's a neat trick for this problem and it's possible to obtain the answer in a rather elementary...
  16. B

    What causes the peak in the thermal noise spectrum of an RLC circuit?

    Hello! Below is a figure of the thermal noise spectrum of an RLC circuit from a certain experiment. I am not sure I understand the shape. The spectrum is peaked around the resonant frequency. However, in thermal equilibrium, I would expect that the electrons to have random motions, so for a...
  17. J

    Calculating Signal to Noise due to thermal noise

    The total noise from other sources and thermal is ##N = N_{other} + N_{thermal}## ##N_{175}/ N_{275} = (N_{other} + \sqrt{2k(175)R\Delta f})/( N_{other} + \sqrt{2k(275)R\Delta f})## I'm not sure how to simplify the expression as ##N_{other} ## is unknown. If I assume ##N_{total} =...
  18. P

    Problem on thermal radiation and lenses

    I know that the Sun is at a very far distance from the lens, so I assume the rays are parallel and the image is formed at the focus (500mm away from the centre of the lens). How do I calculate the diameter of the image? The hint to solving this problem says that "The angular diameters of...
  19. Hansol

    Physical meaning of thermal conductivity tensor

    Good afternoon everyone! I've learned that thermal conductivity has a form of second-rank tensor. As you know, diagonal components of stress tensor mean normal stress and other components mean shear stress and like that do off-diagonal components of thermal conductivity tensor have some special...
  20. D

    Tracking thermal expansion of an aluminium load cell

    Hi all, I am having trouble getting repeatable results from a linear regression formula that simply uses temperature vs load cell output especially with rapidly increasing/decreasing temperatures. This appears to be a result of the thermal co-efficient of our temperature sensor being almost...
  21. D

    Chemistry Volume of a Gas from a thermal decomposition

    Ca(HCO3)2 -> CaCO3 + H2O + CO2 First I evaluate the moles of calcium carbonate (don't mind the units, just to save time) ##\frac {80.0}{40,00+12.01+3*16,00}= 0,799 mol## From the equation, correct me if I am wrong , one mole of CaCO3 is proportional to one mole of CO2, so from this I can...
  22. R

    Engineering Thermal expansion coefficient calculation — where is my mistake?

    Hello everyone, Once I got through the VDW state equation I came to the expression of the thermal expansion coefficient. When I place the values I get an illogical answer. Is there a problem with the units? (Please ignore the values) Thanks. This is the unit equation I get to and get stuck:
  23. B

    Glass Thermal Energy: Solid Glass Beam w/ Spiral Column

    Could I put this on here for answers please ? If produced a solid glass beam with a spiral column thorough the middle of it would the core be hotter or cooler than the surrounding air? If colder could it be use in conjunction with ground source technology to produce hot water? I not sure how to...
  24. R

    Engineering Heat Capacity and the Coefficient of thermal expansion

    thanks!
  25. E

    I Kirchhoff's law of thermal radiation/Infinitesimal volume

    Is there a form of Kirchhoff's law of thermal radiation that applies to infinitesimal volumes rather than optical surfaces of materials?
  26. Kathhhriine

    Rate of flow - thermal physics

    Frankly, i don't even know how to start this. I deducted from the solution, that they must have used power/(specific heat capacity x temperautre), however i don't understand how that will give the rate of flow of air. Could anybody help, please?
  27. Kathhhriine

    Thermal physics -- Converting the internal energy of argon atoms to temperature

    I tried using U=3/2 NKbT, but i don't seem to get the correct answer..
  28. A

    Thermal Machine: Solving for Q23 to Complete the Otto Cycle

    1-->2 (adiabatic) $$P_1V_1^γ=P_2V_2^γ$$ $$P_2=18,4.10^5Pa$$ $$T_1V_1^{1-\gamma}=T_2V_2^{1-\gamma}$$ $$T_2=429,32K$$ 2-->3 (isochoric) $$\frac{P_2}{T_2}=\frac{P_3}{T_3}$$ $$\frac{18,4.10^5}{429,32}=\frac{P_3}{T_3}$$ 3--> 4 (adiabatic) $$P_3V_3^{\gamma}=P_4V_4^{\gamma}$$...
  29. FEAnalyst

    Can thermal expansion cause buckling in a compressed plate?

    Hi, in the Timoshenko’s book "Theory of elastic stability" one can find a case of simply supported rectangular plate uniformly compressed in one direction (compressive load is applied to shorter edges). The formula for critical load is: $$N_{cr}=\frac{\pi^{2} D}{b^{2}} \left( \frac{b}{a} +...
  30. rannasquaer

    MHB Thermal Diffraction and Expansion

    Does anyone know how I can relate the diffraction in a circular crack to the thermal expansion of that crack? Something that I relate the gap radius with the distances between the light and dark fractions of the diffraction figure.
  31. C

    A How are the thermal expansion of a solid and the stress tensor related?

    My idea is this: tensor stress is directly related to the internal pressure of a solid. That is to the force that the neighboring atoms exert each other in relation to a unit of surface. When I heat a solid we can have the phenomenon of thermal expansion: this is connected to the fact that a...
  32. H

    Intro Physics Undergrad Thermal Physics recommendations

    Hey guys, I have Thermal as a course in this (undergrad) semester and the teacher is very bad. Any book recommendations for me to study entirely on my own? This is what we have to cover in the course:
  33. A

    Thermal energy/ heat in a parallel connection

    In a parallel connection heat is produced. R1 = 5 Ohm R2 = 10 Ohm What is the relation of W1/W2? 1:4 1:2 2:1 1:8 3:1 I’d tend to say 1:2, but I am not really sure…
  34. A. Neumaier

    A Many Worlds versus Thermal interpretation

    The two volume treatise Bryce DeWitt, The global approach to quantum field theory, Oxford Univ. Press 2003. which discusses the canonical approach to dynamical quantum gravity, is probably responsible for the fact that the many worlds interpretation (MWI) of quantum mechanics has a sizable...
  35. f95toli

    A Number of thermal photons in a real (finite Q) cavity

    This is probably a common questions, but I can't find it answered anywhere... It is of course well known that the average number of thermal photons in a mode can be calculate from from the B-E distribution: <n>=\frac{1}{e^{hf/k_BT}-1} The usual understanding of this is that what we are...
  36. T

    Thermal penetration depth experiment

    I doing an experiment that involves thermal penetration of copper. Please advise me where to post if I choose the wrong spot. This experiment is being done with what I have on hand and my ability to work the materials. Materials 2.75 gal pot of water 6qt pressure cooker 100+lb of stripped...
  37. TachyonLord

    A Books/Resources related to the thermal model for particle production

    I can only find papers relating to how they've used the model but nothing about the model.
  38. imselva

    Coefficient of Thermal conductivity

    We know that, Conduction Heat Transfer Q = KA(t2-t1)/thickness K is the coefficient of thermal conductivity. If T2 = 1020°C and T1= 22°C also consider we know A and thickness value. K depends on temperature. K varies with temperature. For all the materials we have a tabular data of K for...
  39. T

    What does the thermal expansion lab data reveal?

    So guys I had physics lab where we used Steam Generator, Pasco interface and Capstone. In a nutshell there is graph attached below and formula, please write the solution with this formula.
  40. imselva

    What is the Equilibrium State in Radiation Heat Transfer?

    I have two bodies, one at a higher temperature say 1000°C (Body A) and the other is at 22°C (Body B). Body A emits Radiation (Surface to Surface interaction). The temperature of Body A is maintained by a constant supply of Energy. The Body B will absorb the Radiation Energy from Body A, and its...
  41. I

    Question about thermal physics -- Ice cubes melting in water

    First, I calculated the heat required for the ice to melt: Q=mLf Q=0.150×330 Q=49.5 J Then, I calculated the final temperature of the water by forming the following equation: Q=mcΔT −49.5=(0.15+0.35)×4200×(Tf −80) Tf=80.0 degrees Celcius But the answer says 32 degrees Celsius.
  42. Seyit KAPLAN

    How is the thermal conductivity affected by magnetic field?

    Hello, I'm searching for how magnetic field affects the thermal conductivity of the metal (such as steel in solid form). If someone suggests any article about it will be very helpful.
  43. Petronius

    Thermal energy question: Final temperature of a solution

    Hello, thank you for taking the time to read this.. I hope I followed the formatting correctly and this post complies with the expectations of the forum. I solved the equation but my answer seems too low. I tried it again and arrived at the same answer. I also had doubts if it was acceptable...
  44. F

    Best outside color for thermal insulation

    I'm wondering if the outside color has an influence on the thermal depletion of things such as a thermos, a wall, etc. Assuming, obviously, there's no sunlight hitting on them. It certainly has, but what difference percentage can we typically expect for example for bottles such as the ones on...
  45. E

    At what range does a conservative force contribute to the thermal U?

    Suppose we define our system to contain a few deformable bodies that exert gravitational forces on each other, and are consequently moving towards each other in some vague sense. We might want to express the total energy of the system as the sum of the mechanical energy and internal energy...
  46. Zaya Bell

    How do molecules radiate photons and contribute to thermal radiation?

    If a substance gains energy, it's molecules vibrate faster and thus the material increases temperature. My question is if heat lost through any other means but radiation is zero, how exactly does these molecules radiate photons?
  47. Paper glider rides a thermal!

    Paper glider rides a thermal!

    • Swamp Thing
    • Media item
    • thermal
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    • Category: Pop Science
  48. C

    IR thermometer vs thermal imager

    Isn't it both use the same exact principle? An infrared thermometer versus a thermal imager? Why is it that the thermal imager is not for body temperature (as indicated below) while the infrared thermometer is for body temperature. I think they both scan the same blackbody of the physical body.
  49. LordGfcd

    What is the continuity condition for the heat flux through a boundary?

    Assume there is a boundary separates two medium with different heat conductivity [κ][/1] and [κ][/2]. In one medium, the temperature distribution is [T][/1](r,θ,φ) and on the other medium is [T][/2](r,θ,φ). What is the relationship between [T][/1] and [T][/2] ? Is it - [κ][/1]grad [T][/1]=-...
  50. U

    I Will thermal disturbance change an atom's spin?

    If thermal motion (collision of atoms) changes the direction of an atom, will that change the direction of spin? If so, how much time does it take from the change in the atom orientation to the change in the spin?
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