Adiabatic Definition and 498 Threads

Homework Statement Suppose that one mole of an ideal gas expands in a quasi-static adiabatic process from P1 = 1 Pa and V1 = 1m3 to V2 = 8m3. What is the change in the pressure and the entropy of the gas? Homework Equations PV\gamma=constant The Attempt at a Solution I can't come...

I an working on a problem in the text "Mechanics and Thermodynamics of Propulsion" 2e. The problem states a perfect gas with molecular weight M=20 and a specific heat ratio of Y=1.2 expands adiabatically in steady flow from a pressure of 6MPa, a temperature of 3000K, and a velocity of 200 m/s...

I hope someone in here can help me out of this problem. I know that for calculating the change in entropy of a system (\Delta S) we can use this formula : \Delta S=\intδq/T Well the problem is here, when we calculating ΔS for an adiabatic process we know Q= 0 so ΔS=0 in this process, but...

What's the difference?

I'd just like to check my answer, it seems too big Homework Statement Air initially at 20◦C is compressed by a factor of 15. What is the final temperature assuming that the compression is adiabatic and \gamma ≈ 1.4 the value of \gamma for air in the relevant range of temperatures? By what...

Homework Statement In a quasistaic adiabatic process in a monatomic ideal gas PV^5/3 = constant [DO NOT PROVE]. A monatomic ideal gas initially has a pressure of P0 and a volume of V0. It undergoes a quasistatic adiabatic compression to half its initial volume. Show that the work done on...

isothermal and adiabatic please help! Homework Statement Hello, I have been stuck on this problem for about an hour so any hep would be greatly appreciated! One mole of argon at 25 degrees C and 1 atm pressure is allowed to expand reversibly t a volume of 50 L (a) isothermally (b)...

Homework Statement An Ideal Gas at 300K has a volume of 15L and a pressure of 15 atm. Calculate the change when the system goes under a reversible adiabatic expansion to a pressure of 10 atm. Gamma = 5/3. Cv = 1.5R. q = 0(definition of adiabatic processes).Homework Equations dw = P DV...

Homework Statement For a particular sample of monatomic gas, the rate of change of pressure with volume under isothermal conditions is -2 x 10^7 Pa m^-3. Calculate the rate of change under adiabatic conditions. Homework Equations isothermal: dP/dV = -2 x 10^7 Q = nRTln(Vf/Vi)...

Can you help me with this problem? An ideal gas is compressed adiabatically. The work done over it is 200 J. How much will the internal energy change? A) 200 J B) 100 J C) -200 J D) 0 J Which formula do you use to solve it? Thanks in advance!

Homework Statement Is this impossible: (yes or no) During an adiabatic process, 37 J of work was done on the system. Homework Equations Delta U=-W The Attempt at a Solution I think it is impossible because it says work is negative. I am not sure though.

Homework Statement A monatomic gas has V1 P1 and T1 (volume pressure and temp) at state 1 The gas then goes through the following process adiabatic expansion to stage 2 (exapands to twice its volume) isovolumetric heating so it gets back to T1; stage 3 isothermal compression back to...

I came up with this question a while ago, and my Physics teacher and I just can't get the math to work. Here it is: A cylindrical container of base area A and height h holds some number of moles, n, of an ideal gas. One end of the container is movable, and a force F is applied to that...

Homework Statement The fireball of a uranium fission bomb consists of a sphere of radius = 15m and temperature 300,000K shortly after detonation. Assuming that the expansion is adiabatic and that the fireball remains spherical, estimate the radius of the ball when the temperature is 3000K...

If a quantum system is subjected to a time dependent Hamiltonian with one parameter lambda, then its entropy does not change provided lambda is changed slowly enough between two values. How can this be proved rigorously? The http://en.wikipedia.org/wiki/Adiabatic_theorem" is not enough, since...

I have been asked to show that if an ideal gas is compressed isothermally its compressibility is 1/P whereas if the same gas is compressed adiabatically its compressibility is 1/yP Where y is gamma I have managed to do the first bit about isothermal compressibility, but cannot work out...

Homework Statement 4 liters of an ideal diatomic gas are compressed in a cilinder. In a closed process, the following steps are taken : 1) Initial state : p_1 = 1 atm = 1.013*10^5 N/m^2 and : T_1 = 300 K 2) Isochoric proces resulting in : p_2 = 3.p_1 3) Adiabatic expansion resulting in...

Homework Statement I'm in a rutt for a tutorial question: The question is basically to show that the work done during a reversible adiabatic expansion of an ideal gas is W = (P1V1 – P2V2)/(1 ‐ γ) ... Y is gamma Homework Equations The Attempt at a Solution I've got so...

I'm having a hell of a time understanding this. Can anyone give me a hand? How is it derived? etc?

As the title says. If we have a system which can't exchange heat with the environment that is, by definition, an adiabatic process. Is it possible that in that situation the pressure lowers, the volume increases and the temperature stays the same?

I modified an incorrect derivation of entropy from phase space volume of a gas in the Wikipedia entry http://en.wikipedia.org/wiki/Adiabatic_invariant "Adiabatic expansion of an ideal gas" and I'd like to know if my modified derivation is also incorrect somehow. I realize it doesn't include...

Homework Statement Calculate the entropy for an irreversible adiabatic expansion of an ideal gas which goes from (Vi, Pi) = (9.01L, 3.00 bar) to (Vf, Pf) = (15.44L, 1.50 bar)Homework Equations \DeltaS = \int dq_{reversible}/T The Attempt at a Solution I understand that entropy is a state...

Using dU = dW, \frac{f}{2}NkdT = -PdV I eventually came to T^\frac{f}{2}V = \mbox{constant} I tried to then get it to the form in the book - PV^\frac{f+2}{f}=\mbox{constant} using the formula PV = NkT: \left(\frac{PV}{Nk}\right)^\frac{f}{2}V=\mbox{constant}...

In "Introduction to Thermal Physics" - Schroeder, the derivation for adiabatic compression: V^\gamma P = \mbox{constant} is derived by assuming the compression is still slow enough to be quasistatic. However, I'm still a bit confused with how slow is 'slow'. Quasistatic compression needs...

Is an adiabatic process isothermal also? Can anyone please tell me if it is necessary for an adiabatic process to be isothermal? Please explain with example.

Homework Statement A simple hydrostatic system is such that PV^k is constant in a reversible adiabatic process, where k > 0 is a given constant. Show that its internal energy has the form E=\frac{1}{k-1}PV+NF(\frac{PV^k}{N^k} where f is an arbitrary function. Hint: PV^k must be a function of...

Homework Statement Show that when an ideal gas expands adiabatically, the temperature and pressure are related by the differential equation: dT/dP = (2/f+2)(T/P). Homework Equations PV=NkT VT^(f/2) = constant V^(gamma)*P = constant The Attempt at a Solution I started off with the formula...

Homework Statement One mole of an ideal gas at 0 celcius is subjected to changes below, calculate the change in entropy of the gas: i) Gas is expanded reversibly and isothermally to twice its initial volume. DONE - 5.76 J/K ii)A similar expansion to i. is performed reversibly and...

Homework Statement One mole of Ar initially at 325K undergoes an adiabatic expansion against a pressure Pexternal=0 from a Volume of 10.5L to 95.0L. Calculate the final Temperature using Ideal Gas and Van der Waals equations of state. Assume Cv,m=(3/2)R. Homework Equations PV=nRT...

Homework Statement Is it possible to have a process that is both adiabatic and isothermal. Homework Equations The Attempt at a Solution I think the answer is no. Because when a system is doing an adiabatic process, the total energy of this system must be changed. For an...

I'm having a lot of trouble with an adiabatic mixing process. This is what I know: There's an airstream coming from outside and its temperature is T1=5 'C, its relative humidity being \varphi1= 90% at a rate of 20 m3/min. Another airstream is coming from inside and its temperature is T2= 25...

Homework Statement An adiabatic process is performed on 15 moles of an ideal gas. The initial temperature is 320 K and the initial volume is 0.80 m3. The final volume is 0.40 m3. The adiabatic constant for the gas is 1.44. How much work is done by the gas? The answer is -32kJ Homework...

In polytropic process internal energy change is=mCv(T2-T1)? why is it not mCp(T2-T1)? Why are we not taking specific heat at constant pressure?

Why is there a difference when calculating pressure temperature and volume using the combined gas law, or when using adiabatic relations? As an idiot I am very confused. Why must I use a very similar equation to calculate the final temperature of an ideal gas but resulting in very different...

Homework Statement Consider an adiabatic chemical reaction which results in the system being compressed. Assume an infinitely large surrounding. Draw a pressure-volume plot for the process. Indicate the points corresponding to your final and initial volumes o the plot. Indicate at which...

Hi there! I have to determine the work done of a reversible adiabatic expansion. Becauce the system is adiabatic: Q = 0 so \DeltaU = Wrev Becauce both the pressure and the volume changes I can't use W = pex\DeltaV. Homework Statement Cv, Cp, Ti, Tf, Pi, Pf, Vi, Vf are known The Attempt...

Hi everybody, this is my first post on your forum and i hope someone can help me :) the problem is i can figure out how to approuch this problem :s i do know that the process of the air descending is adiabatic but still i can't get it :( thanks for your help guys in advance. Homework...

Homework Statement One mole of a monatomic ideal gas is taken through the reversible cycle shown below. Process bc is an adiabatic expansion, with Pb = 10.0 atm and Vb = 1.00 x 10-3 m3. Find (a) the energy added to the gas as heat (b) the energy leaving the gas as heat, (c) the net work done...

Homework Statement Air turbine used to drive a application in a machine shop is supplied with air from the factory air supply main where the conditions are 0.6 MN/m^2 and 31 ºCthrough an adiabatic throttle valve which reduces the pressure to 0.3 MN/m^2. In the turbine the air expands...

Homework Statement Electrical current is passed through a resistor immersed in a liquid in an adiabatic container. The temperature of the liquid is varied by 1 degree Celcius. The system consists solely of the liquid. Does heat or work flow across the boundary between the system and...

An explosive liquid at temperature 300 K contains a spherical bubble of radius 5 mm, full of its vapour. When a mechanical shock to the liquid causes adiabatic compression of the bubble, what radius of the bubble is required for combustion of the vapour, given that the vapour ignites...

Disclaimer: English is not my native language. I'll try to do my best, but i could put some inappropriate term somewhere, if so please forgive me and feel free to correct me, the more i learn the best :P Hello guys. I'm new here, but i don't really think that this post could be addressed to...

Homework Statement At ground level in Colorado Springs, Colorado, the atmospheric pressure and temperature are 83.2 kPa and 25 C. Calculate the pressure on Pike’s Peak at an elevation of 2690 m above the city assuming an adiabatic atmosphere. Known Patm = 83200 Pa T0 = 25° C z-z0 = 2690 m...

Homework Statement A heat engine uses a diatomic gas that follows the pV cycle shown in Figure. Part 2→3 is adiabat, part 3→1 is isotherm, V=1040 cm3, P=100 kPa, T1=212 K. Determine the pressure at point 2. Determine the volume at point 2. Determine the temperature at point...

Hey. I'm supposed to calculate the work done in an adiabatic process, B-C, and I only know the values of the temperatures and the volume in the first point (point B). It is not known if it is a mono or diatomic gas, therefore i don't know the value of gamma. I've tried T*V^(gamma-1)=K and the...

how to create an adiabatic environment

Homework Statement http://img30.imageshack.us/img30/9954/72990922.jpg The Attempt at a Solution I would say the answer to (a) was no but that would be a guess. Does it have to do with the fact that it's done instantaneously, whereas to achieve anything like an irreversible process...

Just say an ideal gas goes through process such as isobaric, isochoric, quasistatic, adiabatic etc, is there any special cases where entropy is conserved, or am i thinking enthalpy. Also how is enthalpy found in adiabatic processes?

Homework Statement Ok, i have a cycle that goes from "a to b", via isobaric expansion, than from "b to c" vis isochoric decrease in pressure, and "c to a" via a adiabatic compression. Each occur under quasistatic conditions I just want to double check I've got the, changes in work, heat...

Homework Statement i have to find the W done in an Adiabatic, Quasistatic compression and I am not having much luck. Ive calculated it using (delta)U = Q + W, since Q = 0, hence W = change in internal energy However i want to calculate it using W = -(delta)P*V The Attempt at a Solution My...