Thermodynamics Definition and 1000 Threads

Homework Statement 5 kg of water at 60 degrees are put in contact with 1 kg of ice at 0 degrees and are thermally isolated from everything else. The latent heat of ice is 3.3x105 J/kg. What is the change of entropy of the universe when 100J of energy are transferred from the water to the ice...

Homework Statement A vessel divided into 2 parts by a partition, contains 4 mol of nitrogen gas at 348.15K and 30 bar on one side and 2.5mol of argon gas at 130C and 20bar on the other. If the partition is removedand the gases mixes adiabatically, and comletely, what is the change in entropy...

Homework Statement I want a detailed understanding of the temperature drop of a boiler when water is lost from a leak. I have a temperature recording of a leak that lasted for an hour and caused the temperature to drop from 170oC to 150oC when 2.55m3 of water was lost. I have tried using steam...

Homework Statement Only Number 1, not number 2 Homework Equations Dew Point Temperature T = Saturated Temperated at Vapor Pressure Partial Pressure = (mole fraction) x (Mixture Pressure) The Attempt at a Solution The dew point temperature is only dependent on the pressure of the water...

Just a basic question. It's as the title says, If I'd want to determine the latent of oils (or any material for that matter), is the same methodology used for determining the L.H. of ice applicable? (e.g...

Homework Statement Integrate w=–∫vDP from 2 to 1 and get k(P2V2-P1V1/1-k) The equation is used for steady flow, reversible and Ideal gas Homework EquationsThe Attempt at a Solution I'm not sure how to get the result

Homework Statement [/B] A horizontal cylinder with length L=1m and section S=2*10^(-3) is divided in two parts by a piston. In theese compartments is air at pressure p0=10^5N/m^2 and same temperature. The piston move with h=0,4m from initial position. Which is force to hold piston in this...

1. The problem statement, all variables, and given/known data Q1 Resistance at 0 degrees Celsius = 3840 ohms Resistance at 100 degrees Celsius = 190 ohms Resistance at ? degrees Celsius = 2300 ohms a. Calculate the temperature of the water according to calibrated thermistor assuming the...

Homework Statement : [/B]A thermally insulated closed copper vessel contains water at 15°C win the vessel is shaking vigourously for 15 minutes the temperature rises to 17°C the mass of the vessel is hundred gram and that the water is 200 g capacities of copper and water for 20 J/kg K and 4200...

Homework Statement Assume 1.500 mol of a monatomic ideal gas is compressed from 3.00 L to 1.00 L. a. If the initial and final temperature is 10.0 °C, what are the initial and final pressures (in atm)? b. How much work input (in kJ) is required if a reversible isothermal path at 10.0 °C is...

Hi. This is technically an assignment question, but it's not really a problem that I have to solve. It's more of an investigation so I thought this would be a more appropriate place to discuss it. The question basically asks you to compare the thermodynamic cycle of water in a typical thermal...

Homework Statement The Equation of State and the expression for the entropy for a sample of salt water is given by: V = V_{0}(1 + \beta(T - T_{0}) - \gamma(P - P_{0})) S = S_{0} + C_{v}ln(T - T_{0}) + \frac{\beta}{\gamma}(V - V_{0}) where the subscript 0 denotes a reference state, the...

Homework Statement A spring (k = 500 N/m) supports a 400 g mass which is immersed in 900 g of water. The specific heat of the mass is 450 J/kg and of water is 4184 J/kg. The spring is now stretched 15 cm and, after thermal equilibrium is reached, the mass is released so it vibrates up and...

Can we measure 'absolute entropy' of a system. Also can entropy become zero at 0 kelvin.is it possible only theoretically?

Why is the pressure used in flow work the pressure of the fluid? If the fluid was say at 10kPa and the external pressure was at 0Pa, why don't we use the 0Pa in our calculations for flow work, since it's the external pressure that's the resistance? Or is it not possible to have this difference...

Homework Statement I need to prove the following equation: Homework Equations The 4 maxwell relations and their derivations: https://en.wikipedia.org/wiki/Maxwell_relations The Attempt at a Solution I started out with the fundamental equations of dU=TdS - PdV and as dS=0, and Cv=(dU/dT)v; I...

Hello everyone, I'm doing revision for a final exam in Thermodynamics and i found this exercise i can't solve: A particular material has a latent heat of vaporization Δh, constant along the coexistence curve. One mole of this material exists in two.phase (liquid-vapor) equilibrium in a...

So when my dad first explained the fundamental idea of thermodynamics to me, that entropy never decreases, he pointed out the odd fact that according to basically all other laws of physics, any motion or reaction could be run backwards and be just as valid as it is run forwards. It would break...

Hi I am an electronics and communication engineer and hence doesn't know about heat transfer or termodynamics. I need to design a system using PID where I need to control the temperature of water in a boiler by controlling AC power to boiler heater. I don't have the datasheet of the heater. I...

Thereis no proof for anything in us other than matter(and energy). Thermodynamics works everywhere. I think we live upto the time our system's Delta G (Gibbs free enery) remains negative. Please friends tell me if my undrstanding is justified.

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...

Homework Statement Please consider ethylene at 152oF and 126 atm. Please determine the molar volume (ft3/lbmole) if Z is determined by Corresponding States Theory. Homework Equations Z=PVm/RmT Vm= Molar volume R=Rm/M M= molecular weight Rm=1545(ft*lbf)/(lbmol*oR) Zc=(Pcvc)/(R*Tc) Tc=283 K...

Hello everyone. I stumbled across a problem while studying for my exam that I cannot confidently answer. Can we assume nitrogen at the temperature of 27˚C and the pressure of 100 kPa an ideal gas? Justify your answer. The definition of an ideal gas is "...a gas whose molecules are spaced far...

Homework Statement A closed, rigid tank contains 2 kg of water, initially a two phase liquid–vapor mixture at T1 = 70°C. Heat transfer occurs until the tank contains only saturated vapor at T2 = 120C. Determine the heat transfer for the process, in kJ. answer choices: 3701kJ 119.4kJ 4835kJ...

Homework Statement A flue gas is cooled from 1100 C to 150 C and the heat is used to generate saturated steam at 100 C in a boiler. The flue gas has a heat capacity given by CP/R = 3.83 + 0.000551 T, where T is in K. Water enters the boiler at 100 C and is vaporized at this temperature. Its...

Homework Statement Water is initially at P = 1 bar and T = 20°C. 100kg of water is pumped to a higher pressure at which P = 10 bar and T = 25°C. Find ΔU and ΔH Homework Equations H = m*h du = c*dT dh = c*dT + v*dP The Attempt at a Solution So far I have looked in my table and found that at P...

Homework Statement 2.00 moles of gas is held in a cylinder with a piston and is initially held at 0.300atm and has an initial volume of 0.200 m^3. The molar heat capacity of the gas at constant volume is 24.94 J mol^−1 K^−1 . The gas is then brought from this initial state (State A) through the...

Homework Statement CO2 is at P=3atm, T = 295K and V=1.2m3. It is isobarically heated to T = 500K. Find ΔU and ΔH Homework Equations dU = cpdT The Attempt at a Solution I am having a hard time in general in this class. I understand that in this problem, ΔP = 0. Does this mean that there must...

I am only aware that the formula has to do with entropy/thermodynamics. I could really use the help on how it applies in physics and what the formula is really about.

From Odum (Father of modern ecology) Ecosystem follows the laws of termodynamics 1st law 2nd law The way the laws have been put it looks alright but they are valid for closed systems only which ecosystems are not. However according to wikipedia apart from having a closed system there are...

Homework Statement The uniform 5 m-long round wooden rod (ρ = 800 kg/m3 ) is tied to the bottom by a string with length 1 m. Determine the inclination angle θ if the water level is 3.5 m. What if the water level is 7m? Homework Equations Fb = ρgV The Attempt at a Solution So I'm really...

I thought this would be the most logical way to post this, but give me some grace if it is not because this is my first time posting on this site (then relinquish the grace and tell me how to do it properly haha). First: When a physics problem says "sliding past point P" does that mean it stops...

For class we have been asked to show how the first law of thermodynamics dU=dQ+dW can be shown to be dQ=(CV/R)*VdP +(Cp/R)*PdV I have an answer, but am hesitant to say it is a final answer. I will admit that while doing the problem I had trouble following what I was doing. Hence my...

Homework Statement The problem is that a Carnot contains Boiling water in the hot reservoir and ice water in the cold reservoir. Given that 0.0400kg of ice is melted in 5 minutes, what is the amount of work done by the engine. Homework Equations Qh/Qc=Th/Tc W=Qh-Qc W=(1-Tc/Th)Qs q=mHf...

Homework Statement A 3-m3 rigid vessel contains steam at 10 MPa and 500 degC. The mass of the steam is? I know this question involves using a thermo-table, I'm just very confused on how to find mass from the given information. Homework Equations Maybe PV=nRT The Attempt at a Solution I...

Homework Statement An insulated piston-cylinder device contains 5 L of saturated liquid water at a constant pressure of 175 kPa. Water is stirred by a paddle wheel while a current of 8 A flows for 45 min through a resistor placed in the water, If one-half of the liquid is evaporated during this...

I am graduate student from structural mechanics of solids and need to learn 1 course from fluids and thermal group which includes fluid mechanics or thermodynamics+heat transfer. I am unsure which one would be better to learn, especially which would be helpful in future for solid mechanics. Can...

Homework Statement A train engine climbs a hill. The engine is 30% efficient. The train has a mass of 12000kg. The hill is 750m in height, with an incline of 20° form the horizontal. Friction exerts a force opposing motion of 8000N throughout the climb. Find w, Qin and Qout for the engine...

Is there a definition for "reversible process" that applies to mechanical systems (such as a block sliding down a frictionless inclined plane) that is distinct from the definition of "reversible process" in thermodynamics? If we apply the thermodynamic definition of "reversible process" to...

Hello! I am a bit confused by the formula ##dU = TdS - PdV##. If I want to compute for example ##\frac{\partial U}{\partial V}## I obtain ##-P##, but how should I proceed to obtain, for example ##\frac{\partial U}{\partial P}## or ##\frac{\partial P}{\partial T}## which are not obvious from the...

Homework Statement Determine electron concentration for both Helium and Nitrogen as a function of pressure at 300K. This is from preliminary task for Energy loss of alpha particles in gases laboratories. It's too late to submit this, I'd just like to understand. Can post more info from the lab...

I have learned that ΔG is the amount of available energy. So to understand it i used a simmple body system rather than chemical reaction,which is the sliding of a block on a fixed wedge(height h and inclination angleθ). 1)my system is ball -earth and rest surrounding both in thermal eqilibrium...

Homework Statement The tires on a bicycle require an air pressure of 80 psig. When isothermally pumped up the bicycle tires, the volume of the air (that was originally in the atmosphere) is reduced by a factor of 5.7. Please determine the work that must be done on each lbm of air that is pumped...

Hello chemists, need some help here. I'm trying to calculate the power output of a certain otto cycle using different fuels, specifically gasoline, ethanol and different combinations of the two like 85% ethanol and 15% gasoline or 50% ethanol and 50% gasoline. However I have found it difficult...

Hi guys, I'm doing some research in papers and literature to solve this problem but I've not found anything useful. I want to know the air velocity inside a pipe by the only effect of natural convection. I've attached a picture of the system right here: I hope you can help me to find the...

Homework Statement Hello, i have the following assignment due for monday and i have truly no idea how to tackle it, i have already tried it many times but all my results have been wrong. the problem is as follows. inside a sealed container is an amount of water: mass=90.26 kg; pressure 9.1842...

Homework Statement Find the average energy ##\langle E \rangle## for (a) an n-state system in which a given state can have energy 0, ε, 2ε, 3ε... nε. (b) a harmonic oscillator, in which a state can have energy 0, ε, 2ε, 3ε... (i.e. with no upper limit). Homework Equations Definition of...

Homework Statement By applying the first law to a quasi static process, show that the entropy can be expressed as S = (16σ/3c) VT3 Homework Equations U = 4(σ/c) VT4 PV = 1/3 U[/B]The Attempt at a Solution I know I should be using dS = dQ/T but it's unclear to me how to use this unless I...

Homework Statement [/B] This is a very basic question. I have a cylinder filled with air having stops at a particular height . First part of the process is isobaric as piston is free to move and P is constant. When piston reaches stops this becomes isochoric process as volume is constant. So...

Homework Statement a system uses monoatomic ideal gas describing the following cycle (quasi static) and basically the p-v graph is a circle,and it starts on the left side of the circle with states A, B, C, D (so that B and D are top an bottom) and so P on A (PA) is equal to PC and VB= VD given...