Thermodynamics Definition and 1000 Threads

Thermodynamics is an interesting subject but all too often students think of it as solving math problems. And indeed most of the problem solving involves calculations which can be quite in-depth, requiring knowledge of calculus. I have been looking for ways to deliver thermodynamics principles...

I have come across this problem from this booklet: https://www.ioc.ee/~kalda/ipho/Thermodyn.pdf

In this particular Question according to Meyer's formula,the value of Cp should be (8.314+5) i.e. 13.314 .But that option is missing. There is another approach to this problem by finding the Adiabatic Coefficient and then finding Cp.I have no problem with that approach. But my initial doubt...

Refrigerators run on Carnot cycle. It is like a heat pump that operates on the reversed Carnot cycle. It utilizes the evaporation of the refrigerant to absor...

Summary:: Seems simple but has me stumped... [Thread moved from a technical forum, so no Homework Template is shown] Hello! I am struggling to use an equation given to me. To provide some context, I am trying to work out the entropy for C2H5OH at 348K. Using provided tabulated data, the...

The Second Law of Thermodynamics is not an easy topic. However, if you understand the concept of direction of thermodynamic processes and heat engines, you w...

Let the new engine, NE, extract heat from a certain subset of these baths, and let heat obtained from the ##i^{\rm th}## bath be denoted by ##Q_i##, and let the heat rejected to the ##j^{\rm th}## be denoted by ##Q_j##. Let the engine perform an amount of work ##W##. Now right beside this...

I figured out stokes law equation but I am unable to proceed further

First of all, I didn't know whether to pick this subforum or the engineering/compsci one, I understand this might need to be moved to a more appropriate subforum. The general approach is fairly obvious, use implicit method to construct the tridiagonal matrix for Thomas method and solve. However...

I eat eggs, ham, peppers, and a pancake for breakfast. I cook the ham and peppers at the same time. For purposes of this question, I have the eggs and the pancake figured out. Given a gas stove, a small, nonstick aluminum frying pan (with lid) and corn oil; If my goals are (in order of...

Summary:: Seeking explanation to classical gas - cylinder - piston problem, not the solution. Problem 1.15 from 7th edition of Introduction to Chemical Engineering Thermodynamics by Smith, Van nes and Abbot) Classical problem, given: - gas in a confined cylinder - piston with weight is placed...

A thermal flask with water of temperature 90c is placed out in room temperature 20c, sealed. How long before it reaches 55c? outer radius and height: 5cm, 25cm volume of water is 1litre. R = 0.5 Km2/W using this equation to solve it combining these two and integrating with respect to T...

Hey all, I am working on a problem that goes like this: The cargo space of a refrigerated truck whose inner dimensions are 12 m 3 2.3 m 3 3.5 m is to be precooled from 25°C to an average temperature of 5°C. The construc- tion of the truck is such that a transmission heat gain occurs at a rate...

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.

<mentor: change title> In thermodynamics, there is a function which, for the three variables x, y, and z, can be given as ##G = xG_x+yG_y+zG_z + N[x\ln(x) + y\ln(y)+ z\ln(z)]+E(x,y,z)## where G_x, G_y, G_z, and N are some constants and E is some arbitrarily complicated term. There is a...

Is there a mathematical explanation for why the work done in the condenser (in process 2 to 3) is zero? I am aware that ammonia does not expand or compress in the condenser, only changes phase, but without knowing that the process takes place in a condenser and only considering the graph...

The solution can be found at https://study.com/academy/answer/an-insulated-rigi... After using the two equations I can't see why (h2-h1)/(u2) should equal (T2)/(T1). Can someone explain why specific heat ratio is equal to temperature ratio?

I have a question about the Second Law of Thermodynamics and the Stefan-Boltzmann law. These quotes are from http://www.ces.fau.edu/nasa/module-2/correlation-between-temperature-and-radiation.php “The Stefan-Boltzmann law, a fundamental law of physics, explains the relationship between an...

Attempt at A Solution Problem 1 Reversible Process - A cylinder of ideal gas at pressure P is in mechanical equilibrium with a piston of area A driven by a spring of force F = PA and thermal equilibrium with a reservoir of temperature T. The piston is moved a small distance dx toward the...

by substituting all values in the euler equation you get most of the terms in the fundamental equation but not (N/No)^-(c+1) How do you get this term?

Hi guys, First of all I'm sorry for my bad english I'll try to be as clear as possible. I have tried to solve this problem to understand the First Law of Thermodinamics: Q+L=ΔE_t In fact I know L (in the current convention) is the work which the envirorment does on the system but I don't...

I am looking for a book/notes on the topics mentioned in the title that would be accessible to an undergrad. I have a background in grad quantum and statistical mechanics, but most resources I found on those topics assume a familiarity with QFT, string theory, gauge theory, and general...

I don't understand how to use output from an NPT molecular dynamics simulation to compute a thermodynamic derivative. I need to compute this (where "d" is a partial derivative, "T" is a subscript that means, "at constant temperature," and "E" is internal energy): -(dE/dV)T I have a simulation...

In Thermodynamics, I have seen that some equations are expressed in terms of inexact differentials, ##\delta##, instead of ##d##. I understand that this concept is introduced to point out that these differential forms are path-dependent, although I am not clear how they can be handled. So, are...

Problem, with state values, and pie chart (Fig 4.20) showing answers: ^ This shows the system in question (Kapitza Liquefaction System). Methane gas enters into the compressor (c), then goes through the first heat exchanger (HX1). Some of it (z) gets routed to the expander (exp). Afterwards...

Why is energy balance for a control volume dE/dt = dQ/dt-dW/dt-dm/dt(ΔH+ΔKE+ΔPE) 0 = dQ/dt-dW/dt-dm/dt(ΔH+ΔKE+ΔPE) whereas for other systems it is ΔE =Q-W-(ΔU+ΔKE+ΔPE) 0 = Q-W-(ΔU+ΔKE+ΔPE) with enthalpy, h = u +pv, replaced by only the internal energy? How is the pv term accounted for...

Hi, I posted a similar question recently and gained some insight on these types of problems. However, I am slightly stumped on how to approach this variation of the problem. So I know that: - there is no net change in enthalpy of the blocks and the engine as the processes are reversible -...

Hi, I am quite confused about how to approach this problem. I have seen variations of this problem where there is a heat engine between two blocks, but in this case the surroundings are massless, so I don't believe that approach will work here. Method: I have first started with the case that...

Hi, just reviewing some thermodynamics from the textbook by Sears and Salinger, having a hard time conceptualizing this one. It's an isothermal change in pressure, so the volumes of the mercury and the air both change to reach equilibrium, but if it's a "good vacuum pump", then won't the right...

Summary:: NO TEMPLATE BECAUSE THIS HOMEWORK PROBLEM WAS MISPLACED IN A REGULAR FORUM Cant do part c, using the steady flow equation I am confused how to continue. Please help! Mainly confused as to what heat transfer loss represents in the steady flow equation and where to go to find the...

Hey guys. I have a room which i want to use as a server room. the devices need to work 24/7 and they get pretty hot. so it is imperative to keep the room cool otherwise the devices will be damaged. I have an air vent to bring cold air into the room for the devices so their fans can suck in cold...

Summary:: In need of help determining the exhaust velocity of a rocket nozzle given temperature and propellant molar mass Greetings and salutations! My name is Robert DeVries, world builder extraordinaire. I have come with questions in search of answers. So for the last few days I've been...

According to the first principle of thermodynamics: ΔU = W + Q Also noting that: W = -P⋅ΔV (Question: This P is the initial pressure or the final?) To find V2: (P1⋅V1) / T1 = (P2⋅V2) / T2 → Therefore, (P⋅V1) / T1 = [(P/5)⋅V2] / T2 → (P⋅V1) / T1 = (P⋅V2) / (5⋅T2) → V2 = (5⋅T2⋅V1) / T1...

In heat engine we define a heat source from where heat is transferred to the system, we say that heat source has a temperature ##T_h## , When we define a Carnot heat engine, the first process we have is an isothermal expansion and we say heat has to come in system through this process and here...

I'd like to apply the 1st law of thermodynamics in a reference frame (RF) moving with constant velocity. We have: ##\Delta{}E = E_{in} - E_{out}## I am limiting myself to rectilinear motion. Suppose we are in a RF moving with a constant velocity ##V##. Let the system consist of a mass ##m##. The...

I've learned that ##W = -\int{P_{ext} dV}##, and only during a reversible/quasi-static process where ##P_{int} = P_{ext}## can we write the work done on the gas in terms of the internal pressure (and consequently use ##PV=nRT## etc. which apply to the internal gas). However, a lot of sources...

I was just reading a set of thermodynamics lecture notes and came across the following In most thermodynamics problems I have done, it is indeed assumed that the piston does not accelerate so we can simply equate forces on the piston. However, I don't fully understand the line of reasoning...

Let's say I have a liter of gas at pressure of 4 atm and T=900K. I use it to move perfect massless frictionless and insulative piston to compress a liter of 1 atm, T=300K gas. When the pressure on both sides is equal and the piston stops moving, will the temperature on both sides of the piston...

The speed of sound in a gas at temperature T is given to be ## v=\sqrt{\frac{\gamma RT}{M}}##, where ##\gamma## is the adiabatic exponent, R is the gas constant and M is the molar mass of the gas. In deriving this expression, we assumed that the compression and expansion processes were so fast...

Hi, I was just wondering about the efficiency of a cycle that is not Carnot cycle. In that case one should use \eta = 1-\left|\frac{Q_{\rm out}}{Q_{\rm in}}\right|, where Q_{\rm in} and Q_{\rm out} are the amounts of heat absorbed and released during the cycle. For instance, I guess that in...

There was a question on "Why salt lower the freezing point of water?"I found the following answer."Thermodynamics teaches that a loss of entropy can be overcome by a gain in so called enthalpy". The loss of entropy by freezing the solution canbe over come at temperature much below 0 degree C...

Just started this topic so I'm not sure if this is the correct way to solve this, any help would be appreciated. mass of object x change in temp x specific heat capacity= heat change in temp= heat/(mass of object x specific heat capacity) Mass= 700kg Specific heat capacity of steel= 0.42kJ/kgC...

Q2: An engine has power of 26.5 kW, needs 9 kg coal during an hour for energy. The heat capacity of coal is 7800 cal/g. Define the engine’s efficiency. Qh= mcΔT = 9000x7800xΔT ( stuck) P=26.5kW(is this the power output of the engine in an hour?) If only I could find ΔT, thenI would be able to...

A short background: My question focuses solely on the part of the refrigeration cycle to do with the compressor, where the cycle begins. The first state is before the refrigerant enters the compressor, and the second state is after the refrigerant leaves the compressor. My goal is to obtain...

I'm wondering if the passage from a classical thermodynamic theory, i.e. which does not resort to an atomistic theory and methods of probability and statistics, to classical (i.e. non-quantum) statistical mechanics, led to new discoveries and especially if it was able to explain properties of...

Hello everyone, I have to write a paper about entropy and how it relates to the laws of thermodynamics, energy, and work. I have taken a deductive approach starting from the zero-th law to the second law of thermodynamics as follows. Entropy is the disorder of a system (Class Video, 2019)...

Black powder has specific impulse of around 80s, while rocket candy has up to 130s of specific impulse. Does that mean I could replace the propellant in a BP cartridge with 80/130 of the weight in rocket candy and obtain the same performance in an idealized gun? (as in without considering...