Thermal physics Definition and 201 Threads

Thermal physics is the combined study of thermodynamics, statistical mechanics, and kinetic theory of gases. This umbrella-subject is typically designed for physics students and functions to provide a general introduction to each of three core heat-related subjects. Other authors, however, define thermal physics loosely as a summation of only thermodynamics and statistical mechanics.
Thermal physics can be seen as the study of system with larger number of atom, it unites thermodynamics to statistical mechanics.

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  1. WeiShan Ng

    I [Stat Phy] What does exhausting the states of a system mean?

    I was reading the *Statistical Physics An Introductory Course* by Daniel J.Amit and need some help to understand a certain passage: In an isolated composite system of two paramagnetic system: System a with ##N_a## spins and a magnetic field ##H_a ## System b with ##N_b## spins and a...
  2. P

    Reversibility in thermodynamics

    Conceptually, why does infinitesimally changing a system allow for a process to be reversible. For example, if we heat a system at temperature T1 to T2 by using a heat reservoir at T2, it is considered irreversible, but if we heat the system with many reservoirs at temperatures T1+dT, T1+2dT...
  3. R

    Problem concerning about thermal physics

    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...
  4. W

    Is the Negative Sign Correct in Freezing Lake Fourier's Law Application?

    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...
  5. W

    What is the Thermal Conductivity of a Diatomic Gas?

    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...
  6. lonelypancreas

    Calculating Net Heat Flow for an Aluminum Disk in a Room

    Homework Statement What is the net heat flow of an aluminum disk (emissivity = 0.05) with radius 10 cm and temperature 293K placed inside a room where the temperature is 300K? Asurface = π*r2 = 0.01π m2 Homework Equations Hnet = A*e*σ(Tradiate4-Tabsorb4) The Attempt at a Solution By simply...
  7. K

    Why Doesn't Decreasing Volume Increase Molecular Speed According to Boyle's Law?

    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...
  8. S

    Studying Bombed Thermal Midterm, Advice for Final Exam

    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...
  9. danyull

    Efficient Heat Engine and Final Temperature Calculation

    Homework Statement Two identical bodies of constant heat capacity ##C_p## at temperatures ##T_1## and ##T_2## respectively are used as reservoirs for a heat engine. If the bodies remain at constant pressure, show that the amount of work obtainable is ##W = C_p (T_1 + T_2 − 2T_f)##, where...
  10. T

    Thermal Physics (Specific Heat Capacity)

    Homework Statement Body X whose temperature is 0 °C is brought into thermal contact with body Y of equal mass and temperature 100 °C. The only exchanges of heat that take place are between X and Y. The specific heat capacity of X is greater than that of Y. Which statement about the final...
  11. VegemiteJuice

    Determining the specific heat capacity of water

    Homework Statement Hi, I have an assignment to determine the specific heat capacity of water using a calorimeter, voltmeter and ammeter, where we connected the calorimeter to a 10V power pack and measured the temp of the water and the readings on the voltmeter and ammeter every minute. I ended...
  12. Schwarzschild90

    Canonical partition function for N ideal gasses

    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...
  13. Willfrid Somogyi

    Heat Extracted and Delivered to Reservoirs in a Heat Engine

    NO TEMPLATE---MISPLACED HOMEWORK So it seems like a pretty simple question, and in all likelihood it is, but my lecturer somehow managed to miss this bit in his lecture notes. A heat engine operates between 500K and 300K with 20% of the efficiency of Carnot engine operating between the same...
  14. S

    Why work done on a system causes heat to flow out of it?

    I don't understand how compression of a gas causes heat to flow out of the container of that gas... Could someone please help? Thank you in advance!
  15. S

    How Does Intermolecular Potential Energy Behave in Ideal and Real Gases?

    Homework Statement In the kinetic model of an ideal gas, it is assumed that: A. The forces between the gas and the container are zero B. The intermolecular potential energy of the molecules of the gas is constant. C. The kinetic energy of a given gas molecule is constant D. The momentum of a...
  16. S

    Estimate vibrational frequency of N2 molecule

    Homework Statement Experimental data for the heat capacity of N2 as a function of temperature are provided. Estimate the frequency of vibration of the N2 molecule. Homework Equations Energy of harmonic oscillator = (n+1/2)ħω C=7/2kB Average molecular energy = C*T But this is an expression...
  17. NatFex

    B Difference between albedo and emissivity?

    This has been asked already, but it was either answered incorrectly or I'm just not understanding it right. I was under the impression that albedo is the ratio of radiation reflected off a body compared to the total incident on that body. Hence black bodies have an albedo of 0 and more...
  18. H

    Thermodynamics or thermal physics

    What are some interesting experiments for doing research in thermal physics or thermodynamics?
  19. K

    Calculating Heat Flow in Composite Sheet with Different Thermal Conductivities

    1. A sheet of rubber and a sheet of cardboard, each 2 mm thick, are pressed together and their outer faces are maintained respectively at 0 oC and 25 oC. If the thermal conductivities of rubber and cardboard are respectively 0.13 and 0.05 W m-1 K-1, find the quantity of heat which flows in one...
  20. jeremyskate

    Thermodynamics resistance temperature scale

    Homework Statement IMPORTANT:There is an error in the statement.α and β are in C not K 2. Homework Equations R=Ro(1 +αt+βt2) The Attempt at a Solution I really don't know what to do because if I isolate t in the equation it will give me the temperature on the ideal gas scale whereas the...
  21. Ascendant78

    Thermal Physics - energy, microstates, and probabilities

    Homework Statement Homework Equations The Attempt at a Solution The first part I'm not worried about, but the second part is worked out in the "relevant equations" section. Honestly, it looks like more magic than a Harry Potter movie going on there to me. I'm at a loss as to what...
  22. neosoul

    Thermal physics junior or senior year

    I am registered for Thermal Physics for this year (my junior year). The online curriculum advises physics majors to take it fall of their senior year. (The class isn't offered in the spring.) I am taking 3 other physics classes as well. I felt inclined to take thermal this fall because I wanted...
  23. Y

    Thermal Physics: Cooling by both Conduction & Convection

    Hi all, I am not sure if the is the right place to post the question being new to the forum, but I am looking for some help with a heat transfer experiment that I ran for my honours thesis. Essentially the aim is to determine if warmed saline fluid bags taped to 3 different types of tree barks...
  24. P

    Temperature of a gas in a container

    A rectangular (simplified) container with rigid surfaces, has a certain mass of ideal gas within it, and it accelerates in free space, undergoing rectilinear motion. There are no dissipative forces. Now, since the container moves, its kinetic energy increases, and since the temperature of the...
  25. VoteSaxon

    What Is the Boiling Temperature of the Liquid Using Van der Waals Equation?

    Homework Statement The bulb of a constant volume gas thermometer is immersed in an ice/water/water vapour mixture at equilibrium and the recorded pressure is 0.400 atm. It is then immersed in a boiling liquid and the pressure is 0.844 atm. Sufficient gas is then removed from the bulb such that...
  26. D

    Compressing ideal gas, show no heat exchange

    Homework Statement An ideal monatomic gas is contained in a cubic container of size ##L^3##. When ##L## is halved by reversibly applying pressure, the root mean square ##x##-component of the velocity is doubled. Show that no heat enters of leaves the system.Homework Equations ##dU = dQ -pdV##...
  27. D

    Mean energy of system with ## E = \alpha |x|^n ##

    Homework Statement If the energy ##E## of a system behaves like ## E = \alpha |x|^n##, where ## n =1, 2, 3, \dots ## and ## \alpha > 0##, show that ## \langle E \rangle = \xi k_B T ##, where ##\xi## is a numerical constant. Homework Equations $$ \langle E \rangle = \frac{ \int_{- \infty}^{...
  28. D

    Entropy change of van der Waals gas expansion

    Homework Statement Consider ##n## moles of gas, initially confined within a volume ##V## and held at temperature ##T##. The gas is expanded to a total volume ##\alpha V##, where ##\alpha## is a constant, by a reversible isothermal expansion. Assume that the gas obeys the van der Waals equation...
  29. T

    Thermal Physics: Questions on change of state

    Hello I am trying to learn about the change of state between solids, liquids and gases but I don't understand exactly how it works. I've been reading material given by my school, but I got these two questions to ask because I can't answer them. These are not questions on the sheet they just...
  30. M

    Equations of state -- Partial derivatives & Expansivity

    Homework Statement Show that the coefficient of volume expansion can be expressed as β= -1÷ρ (∂ρ÷∂T) keeping P (pressure) constant Where rho is the density T is Temperature Homework Equations 1/v =ρ β= 1/v (∂v÷∂T) keeping P (pressure ) constant The Attempt at a Solution I started with...
  31. shyjohn

    PSSSix Chapter 2 - Thermal Physics (sample consult)

    Hi, my name is John and I am working on a textbook called Physics Syllabus Stage Six (PSSSix). I have done a draft of chapter 2, Thermal Physics. Although I have requested if this consultation is suitable for this forum, but yet been replied. This textbook is free (online definitely) or...
  32. Maxee

    [Thermal Physics] Calculating Energy Removal

    Homework Statement A water of mass 300g has been poured into a glass of mass 100g (of specific heat capacity 970Jkg-1°C-1) in a refrigerator. How much energy must be removed to cool the liquid and the glass from 30°C to 7°C? Homework Equations c = Q/mΔT The Attempt at a Solution mwater =...
  33. E

    Kittel Thermal Physics Chapter 2 problem 6

    Homework Statement For the example that two spin systems in thermal contact and attain equilibrium, the product of the original multiplicity function will be the new total multiplicity function, Now, we want to find the probability of the system to be slightly deviated from the equilibrium...
  34. C

    Thermal Physics: Energy change due to compression

    This is not a homework problem but rather a passage from my textbook that I don't understand. I don't think I quite understand the concept of reversible processes. Here is the passage from my book: "Consider a system in the quantum state s of energy Es. We assume Es to be a function of the...
  35. C

    Thermal Physics -- Change of energy from compression

    Homework Statement This is not a homework problem but rather a passage from my textbook that I don't understand. I don't think I quite understand the concept of reversible processes. Here is the passage from my book: "Consider a system in the quantum state s of energy Es. We assume Es to be a...
  36. N

    Schroeder: Intro to thermal physics, Diff. between editions?

    Hi, I'm facing a slight problem with getting a good version of the Schroeder: Introduction to thermal physics. According to my lecturer the newest 2013 international edition by Pearson (ISBN: 9781292026213) is not recommended, as it lacks some aspects. And anyway the course is built around the...
  37. T

    What are the best thermal physics textbooks for self-study?

    Hi again, I'm looking for a book to self study thermal physics/statistical mechanics. I would like one with an abundance of worked examples and problems with solutions as well. I've browsed through a few other threads and found these were the general "good" books deemed by the community...
  38. N

    Thermal Equilibrium of Lens and Disk in Solar Projection

    Lens & Disk The image of the sun is projected on the disk using a lens of radius r<<d and focal length f<<d (d is the distance between the sun and the disk.. The magnification of the lens is M`f/d, so that the image completely fills the disk R`=MR. When the disk reaches thermal equilibrium...
  39. R

    Why is the direction of temperature gradient important in thermal conductivity?

    I'm doing Thermal conductivity and I'm kinda confused on something wrt to the temperature gradient...why is it that ΔΘ in the first case the smaller value minus the larger but in the second example it's the larger minus the smaller?
  40. G

    What is the Behavior of Particle Distribution Near Maximum in Thermal Physics?

    Homework Statement There is a box of volume V that is divided into two equal parts: Left side = V/2 = right side. The problem is: Assume that there are n = (Na/2) + k particles in the left hand partition where k is a small integer ( k << Na). Show that the behavior near the maximum where n...
  41. B

    Thermal Physics Expansion Coefficient Problem

    Homework Statement When the temperature of liquid mercury increases by one degree Celsius (or one kelvin), its volume increases by one part in 550,000. The fractional increase in volume per unit change in temperature (when the pressure is held fixed) is called the thermal expansion coefficient...
  42. B

    Thermal Physics Adiabatic Heating Problem

    Greetings all, My first post here on this forum. I'm currently revising for exams and have got stuck on a question where I'm not sure where I'm going wrong...Question: 1g of iron filings at 500 °C are inserted into a sealed 20 litre vessel containing 1 mol of an ideal monatomic gas at a...
  43. F

    Thermal physics - how are Cp and Cv used?

    Afternoon all. I've have the following equations: Cp - Cv = nR = Nkb Cv = nRf / 2 Cp = nR(2+f) / 2 CvlnT = -nRlnV + const where f is degrees of freedom Do the Cp and Cv just stand for pressure and volume (where both are constant), so for example can the first equation only...
  44. M

    Thermal Physics adiabatic and isothermal compressibilty

    Ok so I found something online but I need to understand this problem Prove that the ratio of the adiabatic compressibilty ks to the isothermal compressibility kr is equal to the ratio of the specific heat at constant colume, Cv, to that at constant pressure, Cp Definitions of the...
  45. M

    Thermal Physics problem: Van der Waals

    [b]1. Find an expression that relates T and V in a process in which the entropy S is constant, by doing the following: a) From thermodynamic identity dS=(1/t)dU + (p/v)dV find the expression for dS as a function of T and V (and dT and dV). b) Integrate the expression found in (a)...
  46. L

    Suggestion on books for Thermal Physics and Statistical Mechanics

    I am planing to study thermal physics on my own as I got an incompetent faculty who doesn't know anything about this subject. I want to have a detailed understanding about the topic. So can somebody suggest me which book I should follow from the following list. 1. Schroeder, Thermal...
  47. F

    Thermal physics - entropy change (latent heat, specific heat etc)

    Hi all, could somebody have a look over my answers for this question please? The value I got for the second part seems quite feeble. Homework Statement The Attempt at a Solution Part a) Key m = mass cs = specific heat bronze cm = specific heat molten bronze Tfus = melting...
  48. NATURE.M

    Equipartition Theorem (Thermal Physics)

    I just wanted to know whether the following formula 3/2kT=K (ave) demonstrates the average kinetic energy per atom in a monatomic gas. And then if 5/2kT=K (ave) demonstrates the average kinetic energy per diatomic molecule. This comes from the fact that the average energy per degree of...
  49. C

    Thermal Physics, energy and temperature

    Homework Statement In section 2.5 I quoted a theorum on the multiplicity of any system with only quadratic degrees of freedom: In the high-temperature limit where the number of units of energy is much larger than the degrees of freedom, the multiplicity of any such system is proportional to ##...
  50. X

    Book for help in stat and thermal physics

    This is a general question. In struggling hard in my stat and thermal physics course, especially with homework from kittel and kroemer. I am looking for another book that would have more examples so that I can have an easier time with home work problems. Would anyone have any suggestions ?
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