What is Thermodyamics: Definition and 267 Discussions

Hello! new here. recently I've developed an interest in the way electricity is produced, I've seen some mechanisms, most of them are steam turbine based. i have a few questions about the topic, mainly about thermodynamics. if i want to create enough energy to move a steam turbine that requires...

Homework Statement A steel ring with a hole having area of 3.990 cm2 is to be placed on an aluminum rod with crosssectional area of 4.000 cm2. Both rod and ring are initially at a temperature of 35.0°C. At what common temperature can the steel ring be slipped onto one end of the aluminum rod...

Obviously expanding the gas cools it down. I'm interested if you could boil water and then expand the high pressure steam to cool it down to 0°C. Or are there subtler thermodynamics that would prevent this?

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 An insulated piston-cylinder device contains 5 L of saturated liquid water at a constant pressure of 150 kPa. An electric resistance heater inside the cylinder is now turned on, and 2200 kJ of energy is transferred to the steam. Determine the entropy change of the water...

1. Homework Statement if a rigid adiabatic container has a fan inside that provides 15000 j of work to an ideal gas inside the container, does the change in entropy would be the same as if 15000 j of heat are provided to the same rigid container (removing the insulation)?2. Relevant equations...

Homework Statement Homework Equations unreliable source of solution: The Attempt at a Solution [/B] I came across this problem while practicing for the final exam in thermodynamic,my attempt: i recall this type of problems are not steady-flow system. Since the change in kinetic and...

Homework Statement In a frictionless piston-cylinder system, there are 3 kg of R-134a initially at 280 kPa and 15 °C. Heat is transferred to the system in the amount 120 kJ. What will the final temperature of the refrigerant be (deg C)? Homework Equations Q - W = ΔU (internal energy) Q - Wb...

I'm confused about the mathematics that led to the equation 4.5.9. Specifically, I'm confused about what the variables that describe U are. From the equation I think temperature T(through beta), chemical potential (through alpha), V (through E_s) and N (through... restriction on the...

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 =...

MODERATOR NOTE - NO TEMPLATE BACAUSE POSTED IN GENERAL PHYSICS I am having trouble attacking this problem properly and getting the right solution, which I do not have. (only know I did it wrong on exam). Anyway, there is picture attached this is a cycle of some working material that has a...

Homework Statement [/B] An ideal gas is compressed to the same volume from the same initial state for both an adiabatic and an isothermal process. In which case will more work be done ? 2. Homework Equations ##dU=dQ - dW ## ##W=\int P\,dV ##(For isothermal) ##W=nc_vdT##...

In case of diesel cycle thermal efficiency is low, because heat addition takes place at constant pressure.so can we introduce some retractable plate which sits below the piston during end of compression stroke,and retracts back after heat addition,thus providing constant volume heat addition and...

We have a glass containing 0.5 liter (0.5 kg) of water whose temperature 100 degrees Celsius. We also have an ice cube with mass 0.01 kg and temperature -10 degrees Celsius. The cube is put into the glass. The glass is then insulated from the outside world, until the cube has melted. What will...

Homework Statement Homework Equations Ideal gas law: $$PV=nRT$$ Workdone by the gas: For Isobaric process $$W=P(V_{2}-V_{1})$$ For Isothermal Process $$W=nRT \ln(V_{2}{/}V_{1})$$ First law: $$U=Q-W$$ The Attempt at a Solution subpart (a) is trivial, all we have to do is to substitute the...

I'm studying Thermodynamics and I'm a little stuck at this problem. 1. Homework Statement Starting with the first Maxwell relation, derive the remaining three by using only the relations: $$\left(\frac{\partial x}{\partial y}\right) _{z} \left(\frac{\partial y}{\partial z}\right) _{x}...

A quantity of ideal gas undergoes an expansion that doubles its volume. Does the gas do more work on its surroundings if the expansion is at constant pressure or at constant temperature? The answer in the book says W at constant temperature gives a greater value for the given case. But when I...

Homework Statement One end of a solid cylindrical copper rod 0.200 m long and 0.0250 m in radius is inserted into a large block of solid hydrogen at its melting temperature, 13.84 K. The other end is blackened and exposed to thermal radiation from surrounding walls at 500.0 K. (Some telescopes...

Self-repost from physics.SE; I underestimated how dead it was. So this follows Schroeder's Intro to Thermal Physics equations 6.1-6.7, but the question isn't book specific. Please let me be clear: I know for a fact I'm wrong. However, it feels like performing seemingly allowed manipulations, I...

MODERATOR'S NOTE: NO TEMPLATE BECAUSE THREAD WAS ORIGINALLY POSTED IN A NON-HOMEWORK FORUM A monoatomic gas is present i n cylinder if its volume increase from 100cm3 to 200cm3 at constant pressure 1*10^5 what is change in internal energy. I tried to solve it but couldn't. I tried to solve it...

Homework Statement a)Helium enters a closed system as a flow of compressed gas at a temperature of 14 K and at pressure p (enthalpy conserved). A fraction α emerges as liquid and the rest as gas at 14 K, both at atmospheric pressure p0. Find an expression for α in terms of the enthalpy H(p) of...

Homework Statement Kinetic energy per mol is 3/2KTHomework Equations Q = nC##\Delta##T U = Q + W W = -P##\Delta##V The Attempt at a Solution 1) internal energy = 3/2NKT 2) heat needed to increase temperature of 1 mol ideal gas by 1 degree at constant volume? Since constant volume, W = 0 Q =...

So, I'm now studying thermodynamics and our teacher proved some time ago the following mathematical result: If f(x,y,z)=0, then (∂x/∂y)z=1/(∂y/∂x)z But today he used this relation for a function of four variables. Does this result still hold, because I'm not really sure how to prove it. If...

The field of quantum mechanics was launched with scientists struggling to understand blackbody radiation. My question is: what is the source of this observed radiation? Is it the nuclei in the matrix of the metal jiggling around ever more energetically as you heat up the metal? Or is it the...

Hi. In all of my question, I mean degrees celsius when I say degree. Think we have a 0 degree ice. we give some energy to it (by a heater) and all of it get into a 0 degree water. How does the kinetic and potential energy of the molecules change? In the book in which I saw this question, it...

Most textbooks include an example of entropy of mixing that involves removing a partition between two (in principle) distinguishable gases, and compare this to the case where the two gases are indistinguishable. What I’ve not yet been able to figure out is what the consequences of this...

Homework Statement Homework Equations internal change = $$\frac{3}{2}n.R.(T2 - T1)$$ Work = P.ΔV The Attempt at a Solution 1) T2 = $$\frac {P2. V2 . T1 }{P1 . V1} = 1.2 * 10^3$$ 2) Q = Internal change = $$\frac{3}{2}n.R.(T2 - T1) $$ $$ = \frac{3}{2} * 1 *8.3*10^{-3}*(12*10^2 - 3*10^2) $$...

I have been trying to understand the role of a cavity as a black body radiator in the derivation of planks black body radiation law but it has left me with 5 main questions: 1. If an object is a perfect absorber it must also be a perfect emitter, meaning that (allowing for a cavity not being a...

Hi .how can i calculate the molar volume and surface tension of nanoparticles ? shoud i have to calculate? or these parameters is available in tables or sth?

Homework Statement [/B] A bimetallic strip is made of metal which has coefficient of thermal expansion is equal to α1 and the other's is equal to α2 at the temperature of T0. The temperature is increased to T0 + ΔT (ΔT > 0). The strip curves as shown in the figure. If both strip have the same...

Hi all. Suppose I have the ideal gas law $$P=\frac{RT}{v}$$If I'm asked about the partial derivative of P with respect to molar energy ##u##, I may think "derivative of P keeping other quantities (whatever those are) constant", so from the formula above I get $$\frac{\partial P}{\partial...

Homework Statement Homework EquationsThe Attempt at a Solution [/B] I am taking the free energy as the internal energy of the ideal gas. Then the average internal energy per unit volume is ## \frac { 3 nk_B T } {2 } ##. So, the correct option is (c). Is this correct?

Homework Statement One cylinder in the diesel engine of a truck has an initial volume of 640 cm3. Air is admitted to the cylinder at 30°C and a pressure of 1.0 atm. The piston rod then does 500 J of work to rapidly compress the air. What are its final temperature and volume? Homework Equations...

While doing some calculations on v_rms using the Maxwell-Boltzmann distribution, I noticed that v_rms and v_avg are pretty similar (https://casper.berkeley.edu/astrobaki/index.php/File:MaxwellSpeedDist.png). In fact, really it's just the choice of using the 1-norm (|v|_avg) vs. 2-norm sqrt(v^2...

How can I calculate the length L of each side of a cubic simulation box with 500 molecules (in Ångstrøm) when I want molar volumes of V1 = 0.6 l/mol?

The third law of quantum mechanics states that a system at absolute zero temperature has zero entropy. Entropy can be conceived as an expression of the number of possible microstates that can produce an identical macrostate. At zero entropy, there should be exactly *one* microstate configuration...

Homework Statement Formulate a proof that the energy minimum principle implies the entropy maximum principle. That is, show that if the entropy were not maximum at constant energy then the enrgy could not be minimum at constant entropy. HINT: First show that the permissible increase in entropy...

1. Robert Dehoff 4.12 A system is designed that permits continuous programmed control of the pressure and volume of the gas that it contains. The system is filled with 1 g atom of helium and brought to an initial condition of one atmosphere and 18 liters. It is then reversibly compressed to 12...

Learning Radiometry, Photometry, Optics, Thermodynamics, Fluid Mechanics(Statics & Dynamics) with great resources. I'm looking for resources for understanding the topics above. I prefer video tutorials as opposed to books but I couldn't find any video resources on Photometry and Radiometry (I...

Homework Statement The constant-volume heat capacity of a particular simple system is c_v = AT^3 where A is a constant. In addition the equation of state is known to be of the form (v-v_0)p = B(T) where B(T) is an unspecified function of T. Evaluate the permissible functional form of B(T)...

Homework Statement A cylinder is fitted with a piston, and the cylinder contains helium gas. The sides of the cylinder are adiabatic, impermeable, and rigid, but the bottom of the cylinder is thermally conductive, permeable to helium, and rigid. Through this permeable wall the system is in...

I am working on problem that has to deal with a jet ejector. For the life of me, I cannot figure out the E-Balance equation for it. Below is a cut away image of the ejector. The fluid is the same so using the ideal gas law I do not think should be included. Any help is greatly appreciated...

Homework Statement Two ideal van der Waals fluids are contained in a cylinder, separated by an internal moveable piston. There is one mole of each fluid, and the two fluids have the same values of the van der Waals constants b and c; the respective values of the van der Waals constant ''a'' are...

Homework Statement The fundamental equation of a system of \tidle{N} atoms each of which can exist an atomic state with energy e_u or in atomic state e_d (and in no other state) is F= - \tilde{N} k_B T \log ( e^{-\beta e_u} + e^{-\beta e_d} ) Here k_B is Boltzmann's constant \beta = 1/k_BT...

Homework Statement [/B] Two ideal gases are contained adiabatically and separated by an insulating, fixed piston that blocks the molecules of gas 2 but allows the molecules of gas 1 through(in both directions). The initial pressures, volumes, temperatures and number of molecules on each side is...

A possible ideal-gas cycle operates as follows: 1. From an initial state (##p_1##, ##V_1##) the gas is cooled at constant pressure to (##p_1##, ##V_2##); Let's call the start and end temperature ##T_1## and ##T_2## 2.The gas is heated at constant volume to (##p_2##, ##V_2##);Lets call the...

Homework Statement This is a question from an exam that my university determined to be so harsh that they allowed resits with uncapped grades. I'm going to be taking such a resit thus I'm trying to figure out the paper: Air at 10oC and 80 kPa enters the diffuser of a jet engine steadily with...

Homework Statement Steam at a pressure of 4 MPa and 400 C and flow rate of 10 kg/s is expanded in a turbine to a pressure of 10 kPa. If the isentropic efficiency of the turbine is 0.85 then the actual power produced by the turbine is? Homework Equations :[/B] ηt= (m(h1-h2))/(m(h1-h2s)) = (W...

I understand the 1st law of thermodynamics developed as a generalization based on experimental observations, in that an exception has yet to be found in thousands of situations, so it is considered to hold true in all possible situations. If that is how it developed, is there any other theory or...

So recently I've become familiar with concepts like specific heat, and we use a formula Q=mcΔT to calculate the Joules necessary to heat up say a kg of water from 50 to 70 degrees celsius. Now I was wondering if there is a equation that incorporates the amount of heat lost to the atmosphere...