- #1
Soren4
- 128
- 2
In a adiabatic process (not necessarily reversible) from ##V_a## to ##V_b## the work can be written as $$W=\frac{p_aV_a-p_bV_b}{\gamma-1}$$ Where ##\gamma= \frac{c_p}{c_v}##
Suppose that the adiabatic process in question (again, not necessarily reversible, so ##pV^{\gamma}## can also not be constant) is also isobaric: then ##p_a=p_b=p## so
$$W=\frac{p(V_a-V_b)}{\gamma-1}\tag{1}$$
On the other hand in any adiabatic process $$W= p(V_b-V_a)\tag{2}$$
The expressions ##(1)## and ##(2)## are different, so which of the two is to be consider the right one in this case?
Suppose that the adiabatic process in question (again, not necessarily reversible, so ##pV^{\gamma}## can also not be constant) is also isobaric: then ##p_a=p_b=p## so
$$W=\frac{p(V_a-V_b)}{\gamma-1}\tag{1}$$
On the other hand in any adiabatic process $$W= p(V_b-V_a)\tag{2}$$
The expressions ##(1)## and ##(2)## are different, so which of the two is to be consider the right one in this case?