# more thermo

For the following question I was able to find the heat transfer and the entropy but I am having trouble finding the work done. When i solved delta E = Qnet - Wnet I got Win = Wout but Im not sure that is correct. I think that i need to solve for the final temp and pressure but again I am stuck there. P1V1/T=P2V2/T2 wont work and since it is air and not an ideal gas PV=RT won't work either. Does anone have an idea?
3.1 One kilogram of air in a piston-cylinder device undegoes a thermodynamic cycle composed of the following reversible processes: 1�¨2 air at 2.4 bar and 250 K is expanded
isothermally to 1.2 bar; 2�¨3 air is then compressed adiabatically back to its initial volume; 3�¨1 air is finally cooled at constant volume back to its initial state. Account for variable
specific heats.

c) Calculated the work, heat transfer, and entropy change for process 2�¨3 (57.3, 0, 0)

I don't understand the meaning of "2 air, "1 air, "3 air etc

You should be able to treat air as a perfect gas, even if the specific heat is not constant.

The work done will be the sum of the integral of P dV for steps 1 and 2. Use the gas law to make P a function of V.

For the cycle, Qin - Qout = Wout

those should be arrows. I think when i used the cut and paste function it messed up!

1. 👍 0
2. 👎 0
3. 👁 98

## Similar Questions

1. ### thermodynamics

3.4 A heat engine operates between two heat reservoirs with temperatures of 560 and 280 K a) The heat engine itself has a temperature of 560 K during heat addition from the 560 K reservoir and a temperature of 280 K during heat

asked by jody on June 15, 2007
2. ### thermo

For the following problem... I found the second pressure by solving P1V1/T1 = P2V2/T2. The Volumes is const so those cancel and then i am able to find the P2. From there i looked at the 1st law and came up with delt U = Qin which

asked by jody on June 17, 2007
3. ### Thermodynamics again.

For the following problem... I found the second pressure by solving P1V1/T1 = P2V2/T2. The Volumes is const so those cancel and then i am able to find the P2. From there i looked at the 1st law and came up with delt U = Qin which

asked by jody on June 16, 2007
4. ### Physical Science

QUESTION GIVEN---Thermal conductors don’t have to be hot to transfer heat. According to Ch.16, explain a situation when an ice cube would still transfer heat to another object it is in contact with. MY ANSWER---Because, the ice

5. ### Physics

Refrigerator Suppose that you want to freeze 1.2 kg of water for a party, and only have 10 minutes to do it. Relying on nothing but your keen physical abilities, a dixie cup, duct tape and a piece of string, you manage to build a

asked by BG on November 28, 2010
6. ### PHYSICS

After 6.00 kg of water at 80.4 oC is mixed in a perfect thermos with 3.00 kg of ice at 0.0 oC, the mixture is allowed to reach equilibrium. When heat is added to or removed from a solid or liquid of mass m and specific heat

asked by HELP on December 1, 2012

After 6.00 kg of water at 77.3 oC is mixed in a perfect thermos with 3.00 kg of ice at 0.0 oC, the mixture is allowed to reach equilibrium. When heat is added to or removed from a solid or liquid of mass m and specific heat

asked by Anonymous on November 10, 2012
8. ### physics

After 6.00 kg of water at 80.4 oC is mixed in a perfect thermos with 3.00 kg of ice at 0.0 oC, the mixture is allowed to reach equilibrium. When heat is added to or removed from a solid or liquid of mass m and specific heat

asked by angie on December 1, 2012
9. ### physics

After 6.00 kg of water at 80.4 oC is mixed in a perfect thermos with 3.00 kg of ice at 0.0 oC, the mixture is allowed to reach equilibrium. When heat is added to or removed from a solid or liquid of mass m and specific heat

asked by g on December 1, 2012
10. ### physics

(a) How much heat (J) flows from 1.00 kg of water at 46.0°C when it is placed in contact with 1.00 kg of 18°C water in reaching equilibrium? (b) What is the change(J/K) in entropy due to this heat transfer? (c) How much work (J)

asked by Justin on July 25, 2013

More Similar Questions