Question

A piston/cylinder device contains one kilogram of a substance at 0.8 MPa with a specific volume of 0.2608 m3/kg. The substance undergoes an isobaric process until its specific volume becomes 0.001115 m3/kg. Find the total work done in the process. Is it work done on or by the system? Show the process on a P-v diagram and indicate the area that represents the work.

Answer 1

Given , Isobaric process where the pressure of the system remains unchanged throughout the process , here

pressure is P = 0.8*10^6 Pa

initial volume is Vi = 0.2608 m^3/kg

final volume is Vf = 0.001115 m^3/kg

the work done is W = P*dV = P(Vf-Vi) = 0.8*10^6(0.001115-0.2608)J = --207748 J

so here the work is done on the system because the volume has been decreased