Examples for Chap. 2
1. The gas undergoes a constant pressure process at 5 bar. Initially, v1  0.20 m 3 /kg .
Work done on the system during the process is 15 kJ. Calculate V 2 in m3 at the end of
the process.
m=0.25kg
2. Air goes through two quasi-equilibrium processes.
∙ Process 1-2: polytropic (n = 1.3), p1  100 kPa , v1  0.04 m 3 /kg , v2  0.02 m 3 /kg
∙ Process 2-3: constant pressure, v3  v1
Sketch the p– v diagram and calculate the net value of W m for the whole processes in
kJ/kg.
Air
Quasi-eq.
3. Calculate work transfer from
the steam to the piston in kJ
during the process from the state
1 to 2 by neglecting the effect of
the change in KE and PE.
1
4. The mass of air is 2 kg and the volume is 0.6 m3. The paddle wheel transfers work to
air at a constant rate of 10 W for 1 hour. Neglecting the effect of change in KE and PE,
calculate (a) v2 at t = 1 hour. (b) u 2  u1 in kJ/kg.
Thermally
insulated
rigid container
Air
2