Adiabatic process Definition and 119 Threads

Homework Statement A nearly flat bicycle tire becomes noticeably warmer after it has been pumped up. Approximate this process as a reversible adiabatic compression. Assume the initial pressure and temperature of the air before it is put in the tire to be Pi = 1.00 bar and Tf 287K . The final...

The low is: dQ=dU+p dV but the specific heat to volumen (in a perfect gas) cte is: C_v = \frac{dQ}{dT} = \frac{dU}{dT} why if in adiabatic proces dQ=0, then C_v \neq 0 ?? http://en.wikipedia.org/wiki/Adiabatic_process#Ideal_gas_.28reversible_process.29

In an adiabatic process PVγ=constant Now I thought the work done by an ideal gas in an adiabatic process was given by the equation here: http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/adiab.html But while doing a GRE question the answer was given as PfVf - PiVi / 1 - γ Is this...

Hello Can we consider the sentence “Adiabatic process cannot decrease entropy” (found for example here) to be true in any circumstances ? Here I do not want to focus on any particular situation. Hence the system is not necessarily a (perfect) gas; the transformation is not necessarily...

Most of the book using PV=nRT for PV^gamma constant for adiabatic process. However, please refer attachment, proving using conservation of energy will also make sense?

Homework Statement A large research balloon containing 2000 m^3 of helium gas at 1.00 atm and a temperature of 15.0 celsius rises rapidly from ground level to an altitude at which the atmospheric pressure is only 0.900 atm (the figure (Figure 1) ). Assume the helium behaves like an ideal gas...

For a reversible process, I imagine it is correct to say that dS = \frac{dq}{T} where all quantities refer to system quantities (not the surrounding). However, for an adiabatic process, dq = 0 . Thus, should it be the case that for an adiabatic reversible process, dS =...

Homework Statement Show that in a reversible adiabatic process, for 1 mole of ideal gas P1V1γ=P2V2γ Where, γ=CP/CVHomework Equations Listed above.The Attempt at a Solution Frankly, I don't really understand what I'm being asked to do.

Homework Statement In a diesel engine, the piston compresses the air-fuel mixture from an initial volume of 630 cm^3 to a final volume of 30cm^3. If the initial temperature of the air-fuel mixture is 45 degrees C and the process is occurring adiabatically, determine the final temperature...

Homework Statement My textbook says that W = i/2Δ(pV) for an adiabatic process. I don't understand :S Homework Equations W=∫pdV The Attempt at a Solution

how is the rapid escape of air from a burst tyre and cloud formation in atmosphere an example of adiabatic process? please explain

Homework Statement Derive an expression for the change in temperature with pressure for an adiabatic process. If a dry air parcel is lifted adiabatically from 1000hPa to 800hPa what is the final temperature if it was initally at 20^{o}C?^{} Homework Equations PV^{k}=constant I derived an...

Hello I'm really confused with this and would appreciate any help. Homework Statement a) Show that the work done on a gas during a quasistatic adiabatic compression is given by: W = \frac{P_f V_f - P_i V_i}{\gamma - 1} b) Show that the work done by a gas during a quasistatic...

I have to find the max cycle pressure, max temp, work input and output for an engine. I have been given the initial air pressure, temp and the volume of the cylinder. Fuel is added at 2.5MJ/kg For the air i have Cv, the index (1.4) and an R value of 287 J/kg K (not sure about this value) I...

Homework Statement 1 kg of H20 goes through a reversible adiabatic proces from 220kPa, 200C to 50C in the final state. What is the pressure final and volume final? Assume S1=s2 Homework Equations Conservation of Energy The Attempt at a Solution Found S to be 7.5080, was...

i'm entirely confused with this. with analyzing each definition: adiabatic process : a thermodynamic process in which there is no transfer of heat if a system is in state (P1, V1, T1) → (P2, V2, T2) if it is adiabatic no heat transfer occurs, if no heat transfer occurs the two states must be...

Homework Statement The question is as following: http://i56.tinypic.com/se547s.png Homework Equations W = F x distance or p d(v) . Potential energy : mgh , k.e : 1/2mv^2 The Attempt at a Solution Well I am stuck on part c, now I am aware that in adiabatic process Internal...

Homework Statement A diesel engine requires no spark plug. The air in a cylinder is compressed so highly that the fuel spontaneously ignites when sprayed into cylinder. If the air is initially at 20°C and is then compressed by a factor of 15 in volume, what final temperature is attained...

Homework Statement On my formula sheet I have this: W=(C/1-y)(Vf^(1-y)-Vi^(1-y)) y=Cp/Cv Homework Equations The Attempt at a Solution I am confused about what the C in C/1-y stands for. My textbook does not even have this formula and I realized that C is not Cp or Cv...

Molecular "work" in an Adiabatic process ? I have studied Adiabatic cooling in connection with a rising parcel of air. I’m confused. I understand that temperature is a macroscopic principle (not a Microscopic); molecules do not have a temperature, only velocity and Kinetic energy. I have read...

My Question - Steam at 200 psi and 600 F flows through a turbine operating adiabatically and exits at atmospheric pressure. For every kilogram of steam flowing through the turbine there are 150 Btu of shaft work delivered. (a) What is the final condition of the exit steam? (b) What is the...

My textbook says that Delta S (sys) > 0 for irrev. ad. proc., closed syst (or see http://www.britannica.com/EBchecked/topic/5898/adiabatic-process if you don't believe me) but since Delta S = 0 for reversible adiabatic process and entropy is a state function, shouldn't Delta S = 0 for...

Hi, In deriving the equation for adiabats : V^{\gamma}P = C. It is assumed that the work done during the process is W = -P \Delta V. But calculating the work done from V^{\gamma}P = C we obtain: W = \frac{C}{1-\gamma}\left[ V^{1-\gamma}_{f} - V^{1-\gamma}_{i} \right] . Also, i believe to...

Homework Statement A cylinder, A, containing a monatomic ideal gas, is fitted with a frictionless leakfree piston. The axis of the cylinder is oriented vertically, as in the figure below, so that the weight of the piston maintains the gas at a constant pressure P0. The cylinder is linked...

What is the concept behind 'irreversible adiabatic process' ? Why is the expression for work done in this case different from that when it is reversible?

Hi all, Sorry if this post is a bit wordy but I've been going round in circles and I thought I'd see if anyone on here can help, it's also my first post so be nice... I've been trying to understand how Newton miscalculated the speed of sound. I know that he thought that the propagation of...

Homework Statement An ideal diatomic gas at 75 K is adiabatically compressed to 40% its original volume. What is its final temperature? Homework Equations delta U = Q - W W = the integral of PdV PVgamma = constant U = 5/2nKT = 5/2nRT (diatomic, ideal gas) The Attempt at a Solution...

Homework Statement a container with air (M = 29 g/mol, treated as an ideal gas). In the container, we have 2.0 L of the gas with p1 = 1.0 atm at T1 = – 50C. The gas is compressed adiabatically to a final volume of 0.5 L. What is its final pressure? Homework Equations I am really not...

Homework Statement One cylinder in the diesel engine of a truck has an initial volume of 600 cm^3. Air is admitted to the cylinder at 35 C and a pressure of 1.0 atm. The piston rod then does 500 J of work to rapidly compress the air. What is the final temperature and volume? I found the final...

Homework Statement Two moles of helium at 27 deg Celsius occupies 20 liters. The gas is expanded first at constant pressure until the volume has doubled, and then adiabatically until the temperature returns to its initial value Treat helium as an ideal monatomic gas and assume that both...

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 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...

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...

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 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 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...

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?

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...

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 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...

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...

Suppose that one mole of a monatomic perfect gas at 27°C and 1.00 atm pressure is expanded adiabatically (i.e. no heat transfer, so that the temperature must fall) in two different ways: (a) reversibly, to a final pressure of 0.5 atm, and (b) against a constant external pressure of 0.5 atm...

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 0.80m^3. the final volume is 0.40m^3. the adiabatic constant for the gas is 1.44 the heat absorbed by the gas in kJ is closest to a. 0 b.+54 c.-14...

Homework Statement twenty moles of a monatomic ideal gas (lambda=5/3) undergo an adiabatic process the initial pressure is 400kpa and the initial temperature is 450K. The final temperature of the gas is 320K. The heat absorbed by the gas in kJ is closest to? a.0 b.+54 c.+32 d.-54 e.-32...

Homework Statement A sample of 1.00 mol of an ideal gas at 300 K and 101325 Pa is expanded adiabatically in two ways: a) reversibly to .5 atm and b) against a constant external pressure of .5 atm. Determine the values of q, w, \DeltaU, \DeltaH, \DeltaS, \DeltaSsurr, and \DeltaStot for each...

Homework Statement During an adiabatic process, the temperature of 5.50 moles of a monatomic idea gas drops from 495 C to 215 C. For this gas, find (a) the work it does, (b) the heat it exchanges with its surroundings, and (c) the change in its internal energy Homework Equations I know...

Homework Statement I have the equation for the internal energy: U = (f/2) * N * k * T, where f is the degrees of freedom, N is the number of molecules, k is Bolzmann's constant and T is the temperature in Kelvin. This can be written as U = (f/2)*p*V using the ideal gas law...