Thermo Definition and 267 Threads

Im building an outside vertical axis wind turbine. i need to build the (about 20) plastic fins that are going to be used to form the helix (which is the wind turbine) im trying to build the fins that are used on the helix wind turbine. a good video of it is on youtube: a crappy picture of...

can somebody help me in solving this problem..thanks.. A gaseous substance whose properties are unknown, except as specified below, undergoes an internally reversible process during which V = (-0.1p + 300)ft cube, when p is in psfa. (a) for this process, find -/ V dp and...

I am having trouble with this question...It is from "applied thermodynamics for engineering technologists" by Eastop (Q5.2 if anyone has it)... The Question: Two reversible heat engines operate in series between a source at 527°C and a sink at 17°C. If the engines have equal efficiencies and...

Homework Statement P=RT/(v-b) - a/(T(V+c)^2) Homework Equations u2-u1= Integral ( Cv dT) + Integral ( T * (dP/dT)v - P) dV The Attempt at a Solution I've differentiated P with respect to T to get R/(v-b)+a/(T^2(V+C)^2 and plugged the relevants back into the equation for...

Hello! This is a question purposed to me by my professor as we went over the mathematics behind the diffusion of heat flow through solids. Many parts of this question are left up to us to create. Here is what i am working with. ***** A m^3 box made of Brick .1m thick has air at 30C...

Homework Statement We are working on some problems for class and we are given statements which I accept as valid but don't know how to prove they are valid. I believe I have to utilize the maxwell relations but the terms seem unfamiliar to me.Homework Equations (1) Partial (d^2f / ds^2)_T = T /...

Why does du/dT = Cv, and same for Cp? Also, i don't understand how Cp/Cv = v, where v is the specific volume. It is derived from: Cv + R = Cp, how is PV=nRT used to get from Cv + R = Cp to Cp/Cv = v? I know n is replaced by m/M to leave Pv=RT where R would equal R(universal gas const)/M...

Can somebody please shed a little light on what this formula represents in the physical world? And how could I solve it to get \Delta H? \left[\frac{d\left(\frac{\Delta G}{T}\right)}{\delta T}\right]_p = \frac{\Delta H}{T^2}

Im studying for the Fundamentals of Engineering exam (coming up April 12!) and came across this Thermodynamics problem in my review book. So the work for an isothermal process is RTA*ln(VB/VA), where VA was previously determined to be 0.103m3. In the solution to the problem, the RTA term...

Problem 1: Homework Statement An ideal gas is heated reversibly at constant volume from T1 to T2. Calculate the entropy change of the system, the surroundings, and the universe. Homework Equations dS = dq/T (reversible change) and dq = CvdT (constant V) The Attempt at a Solution I know how...

Can you help me to extend the BCS theory developed in Thermo Dynamics (TFD) formalism to high-temperature superconductivity?

Homework Statement A rigid vessel of total volume 0.5m3 contains 1kg of air at 15°C initially constrained in a volume of 0.06m3 by a diaphragm. The remaining volume is completely evacuated (pressure = 0). If the diaphragm is burst, allowing free adiabatic expansion of the air, determine...

solved Thanks

Could you please give me a walk through on how to solve for volume of a substance using the Peng-Robinson Equation of State, given: 1. initial and final pressure 2. initial and final temperature (it is an isotherm) 3. it is frictionless (all work is reversible) P=...

Thermo --> Heat Pump, confirmation. Homework Statement A cooling unit for a fridge has a 100 W power input. Environment temperature is 298 K. The heat which enters the fridge due to defective isolation is 350 W. What is the minimal temperature the fridge can reach? Homework Equations...

I have some equipment that uses an older refrigerant that I am having a hard time finding any uselful data on. It is r-144a, and if anyone has any idea as to where I could find a thermo properties table on this stuff, let me know. I've been looking everywhere, hundreds of websites, countless...

I have this multiple choice question: Two thin strips of iron and zinc are riveted together to form a bimetallic strip that bends when heated. The iron is on the inside of the bend because: (A) it has a higher coefficient of linear expansion (B) it has a lower coefficient of linear...

Basically, I have a project involving thermally tunable photonic crystals and part of the essay in the run up to the experiment work I want to write a bit on the thermo optical effect, but I have searched in vain for a resource for this. Can anyone suggest a textbook or something online? Thanks.

Homework Statement Saturated liquid water contained in a closed, rigid tank is cooled to a final state where the temperature is 50 degrees C and the masses of saturated vapor and liquid present are 0.03 and 1999.97 kg, respectively. Determine the heat transfer for the process, in kJ...

A question about metal thermo flasks, or metal vacuum flasks if you prefer. I understand the principle of thermo/vacuum flasks. Just to proofed that I read up before posting this question :-) http://en.wikipedia.org/wiki/Vacuum_flask But today I had a look at on of those new-isch thermo...

Homework Statement Imagine some helium in a cylinder with an initial volume of 1 liter and an initial pressure of 1 atm. Somehow the helium is made to expand to a final volume of 3 liters, in such a way that its pressure rises in direct proportion to its volume. (a) Sketch a graph of...

Homework Statement Exhaust gas expands through a nozzle whose isentropic efficiency is 88%. The inlet pressure and temperature are 1.6 bar and 400c respectively. At outlet the pressure has fallen to an ambient level of 1.013 bar. Given that the inlet velocity is negligible, and Cp and...

Hi Here is the question. Suppose someone build a thin spherical shield just above the Earth's atmosphere, and it would absorb all the radiation passing through from the sun. What would the average temperature of the Earth's surface be? (Assuming the avg temperature of the Earth is initially 300K)

we know that $\Delta U$ $=$ $\Delta K_{cm}$ $+$ $\Delta I$ where $\Delta K_{cm}$ is the kinetic energy from cm frame of refrence and the other part is the change in change in potential energy due to various conservative forces. also by first law of thermodynamics $\Delta U$ $=$ $W_{ext} + Q$...

Does the internal energy always depend only on temperature in an ideal gas? Would the equation U=\frac{3}{2}nRT tell us that? are there any other equations? I'm also confused with the area within a cyclic curve on a PV graph. Does the area within the curve represent the work done ON the...

I have this reaction: CH4+4(O2+3.76) --> CO2+2H2O+2O2+15.04N2 Through other calculations and given information I have found that the mass flow rate of the air (the O2+3.76N2) is 25kg/s and the mass flow rate of the fuel is .87 kg/s. I am having the hardest time finding, using these mass...

Homework Statement Consider fuel cell using methane as fuel. Reaction is CH^4 + 2O_2 -> 2H2O+CO_2 Assume room temperature and atmospheric temperature Determine values of delta H (Helmholtz) and delta G (Gibbs) for this reaction for one mole of methane. Question instructed the use of...

Hoping someone can help me here quickly. Trying to get this one question. a perfect gas is compressed adiabatically from 100 kPa and 17C to a final pressure of 500 kPa and final temp of 77C. The work done during the compression is 45 kJ/kg. Calculate the values of gamma, Cv, R and the...

I think I may have posted this in the wrong forum earlier :\ Homework Statement An insulated and initially empty 0.7m^3 tank is connected by a valve to a line flowing air at 50degreesC and 200kPa. The valve is opened until the tank is filled, and then the valve is closed. The insulation is...

Homework Statement An insulated and initially empty 0.7m^3 tank is connected by a valve to a line flowing air at 50degreesC and 200kPa. The valve is opened until the tank is filled, and then the valve is closed. The insulation is then removed from the tank, and a 20degreeC heat sink cools the...

Homework Statement See Attachment The Attempt at a Solution Well to start off I know the gas is monatomic I can find the work done by finding the area under each curve/line: W_{AB} = p_0(2v_0-v_0) = p_0v_0 W_{CD} = (p_0/32)(8v_0-16v_0) = \frac{-p_0v_0}{4} I can't think...

An Ideal monatomic gas at initial temperature T_0 (in Kelvins) expands from initial volume V_0 to volume 2V_0 by each of the 5 processes indicated in the T-V diagram. In which process is the expansion a.)isothermal, b.) isobaric or c.)adiabatic? Explain your answers. d.) In which process...

Homework Statement Rigid tank volume .5m^3 initially evacuated. Tiny hole develops, air seeps in @ 1 bar and 21 degrees C. Pressure in tank reaches 1 bar, slow leak so temp remains 21 deg C inside tank. What's amount of heat transfer? Homework Equations Q=T[S(2)-S(1)] Pv=nRT The...

Well, it's hard to me at least :frown: http://img169.imageshack.us/img169/206/questionzg0.png We are using Schroeders book and this problem was given to us from I assume the book by Reif. We haven't seem to have gotten far enough along in Schroeders book to have gone over this though. I can...

Hey guys, I have been having a really hard time trying to figure out this question. It seems like everything I do, I can not get resonable answers. If you can help me, that would be great. Problem: A 500-L tank stores 100kg of nitrogen gas at 150 degrees K. To design the tank, the pressure...

I have question (probably figured that). I have an open system with mass flow rate going into one inlet and going through two outlets. I have all the terms for the two outlets (mass flow, velocity, area, temp, pressure). However for the inlet I'm missing the Velocity and Area. In solving for...

Hi all. I've heard from students that Thermodynamics and Fluids are really tough classes. I've taken all the physics and the calculus with no problems. What do you guys think about those classes?

Hi, I'm stuck. Can someone help me out? Problem: The properties of a certain fluid are related as follows: u=196+0.718t pv=0.287(t+273) (a)where 'u' is the specific internal energy(Kj kg), t is in degress Celsius, p is pressure(Kn/m2) and v is specific volume (m3 kg).For this...

Okay, I need some help understanding some of the Thermo principles and I found this forum. I hope someone can help. I'm working on Energy Analysis of a closed system. Conservation of energy principle and all that. deltaU = Q-W. Every time I think I know what should be considered work and...

I need a kick start for the following question. We're studying open/closed systems at the moment. "450kg of ice at -18 degrees C is to be removed from a freezer using a jet of steam. How much dry steam at 100 degrees C is required if the final temp of the effluent is 5 degrees C?" This is...

I am trying to make the connection from statistical mechanics to thermodynamics for the isothermal isobaric ensemble. Partition function = (sum of)exp(-BEj-gamma*Vj). I have followed T.L. Hill [Statistical Mechanics, p. 67] but can not understand how he justifies dE=(sum of)EdP, rather than...

unit of work and unit of heat When we study dynamics,the unit of work is in joules which is the energy transferred to a mass which in turn is the product of force and the distance along which the force is applied When we study thermodynamics, the unit of work is again in joules. How...

2-48) The 60-W fan of a central heating system is to circulate air through the ducts. The analysis of the flow shows that the fan needs to raise the pressure of air by 50Pa to maintain flow. The fan is located in a horizontal flow section where the diameter is 30cm at both inlet and outlet...

Im having trouble finding the reasoning here. Work done by the system is called positive? For example, a gas pushing up on a piston and causing the piston to rise. Well, it seems to me that as the gas pushes up on the piston, the gas does work on the piston, so the gas should LOOSE...

Imagine two infinitely large air tanks connected by a long, straight pipe. Tank A is at a higher pressure than tank B, so air is flowing from one to the other. For the sake of argument, we will say there is no heat flux or work into or out of the pipe. Now we put a perfectly insulated...

hello the problem is as stated: a cylinder containing n moles of an ideal gas undergoes an adiabatic process. using W=-\int Pdv and using the condition PV^\gamma=constant, show that the work done is: W=(\frac{1}{\gamma - 1}(PfVf - PiVi) where Pf is final pressure, Pi is initial pressure... I...

Hello; I'm having some difficulties with a thermo question of mine. at low density water vapor conforms well to the ideal gas equation provided the temp is higher than about 320K, but the heat capacity is a function of temperature. The following formula gives the specific heat capacity at...

There are a couple of questions on my practice exam I am stuck on. If you could point me in the right direction I'd appreciate it. 1. A gas is described by the equation PV= RT+aT^2 where a is some gas specific constant. Find (dU/dV)@constant T And provide an expression for the...

OK, I have a piston-cylinder with water. V = 50L = 0.05 m^3 T = 25 C P = 300 kPa m = 49.85 kg specific volume @ 25 C = 0.001003 m^3/kg The water is heated to vaporization with pressure held constant. I need to determine the final temperature and the enthalpy change. I know what the...

a 2.00 mol sample of helium gas at 300K and 0.400atm pressure is compressed isothermally to 1.20atm Find the volume of the gas, work done on the gas and the energy transferred by heat just wondering how to approach this question, and what formulae i hould use where?