## T

(a) Q ^ 0 for the irreversible process

(c) The irreversible process cannot perform work

1.6 Describe a version of each of the four processes in Prob. 1.1 that is closer to reversible than the original process.

1.7 One mole of air is changed from state #1 (580 K, 17 atm) to state #2 (380 K, 8 atm) by two paths, both consisting of two parts.

Path A: proceeds from state #1 isothermally to state #3, then isobarically to state #2. Path B: adiabatic expansion to state #4 followed by constant-volume cooling to state #2.

During the adiabatic expansion from state #1 to state #4, the temperature and pressure are related by:

The portion of path B from state #4 to state #2 is linear on a p - T diagram.

(a) determine T4 and p4 and plot the two paths on a p - T diagram.

(b) what is the molar volume at state #2?

(c) determine the changes in internal energy between state #1 and states #2, 3 and 4. Air is an ideal gas, and its thermal equation of state is:

where R is the gas constant.

(d) Calculate the heat and work for each stage and complete the 2nd, 3rd and 4th columns of the following table. Express Au, Q and W in Joules.

Path |
Au |

## Getting Started With Solar

Do we really want the one thing that gives us its resources unconditionally to suffer even more than it is suffering now? Nature, is a part of our being from the earliest human days. We respect Nature and it gives us its bounty, but in the recent past greedy money hungry corporations have made us all so destructive, so wasteful.

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