The discussion revolves around a thermodynamics problem involving a reversible engine process, specifically analyzing the work done in a cycle and the changes in internal energy across different stages of the process.
Some participants have provided guidance on calculating work and internal energy changes, while others have shared their attempts at finding values for pressure, volume, and temperature at various states. There is ongoing exploration of the relationships between these variables, but no consensus has been reached on the final answers.
Participants are working with specific values for pressure and volume, and there is an emphasis on using the ideal gas law. Some constraints include the need to express results in terms of given variables rather than numerical constants.
The net work done is not zero. Let us go through each part step by step.connorc234 said:Homework Statement
http://i.imgur.com/jmLqca9.jpg
pic of question
Homework Equations
W = p x dV, Q = dU + W etc
The Attempt at a Solution
I know what the different stages are, a-b and c-d are isobaric, d-a and b-c are isochoric
and I believe the answer to a, the net work done in one cycle, is zero as dV is zero.
but the further questions I'm lost. can anyone help or point me in the right direction?
The net work is not zero. How much work is done from a to b? from b to c? from c to d? from d to a?connorc234 said:Homework Statement
http://i.imgur.com/jmLqca9.jpg
pic of question
Homework Equations
W = p x dV, Q = dU + W etc
The Attempt at a Solution
I know what the different stages are, a-b and c-d are isobaric, d-a and b-c are isochoric
and I believe the answer to a, the net work done in one cycle, is zero as dV is zero.
but the further questions I'm lost. can anyone help or point me in the right direction?
Continuing from there, you should first calculate the work done in each process in the cycle, and then add them to give you the answer to a. Let me know if you are comfortable with that.Chandra Prayaga said:The net work done is not zero. Let us go through each part step by step.
1, First, since the given values are p0, V0, we must find the values of pressure volume and temperature of each of the corner states, in terms of these values. Can you do that, and write them down?
Chandra Prayaga said:The net work done is not zero. Let us go through each part step by step.
1, First, since the given values are p0, V0, we must find the values of pressure volume and temperature of each of the corner states, in terms of these values. Can you do that, and write them down?
ok i used pv=nRT taking R to be 8.31Chandra Prayaga said:Continuing from there, you should first calculate the work done in each process in the cycle, and then add them to give you the answer to a. Let me know if you are comfortable with that.
b to c and d to a both zero work since isochoric afaikChestermiller said:The net work is not zero. How much work is done from a to b? from b to c? from c to d? from d to a?
Chestermiller said:This is all correct so far. In your equations for the temperatures, leave the R in (for now), instead of substituting the 8.31. Now, from your results for the temperatures, what is the change in internal energy ΔU from a to b? from b to c? from c to d? from d to a?
Chet