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T  V  1  const (2.7.13)

or in another form

  1
T V 
1   2  (2.7.14)


T 2  V 1 

Analogously
1  
T  p  
1   2  . (2.7.15)


T 2  p 1 

2.8. Work Done in Adiabatic Process

In adiabatic process no heat is added or removed (dQ  0 ).

Therefore, in this case the work done by the system is equal to the change
of its internal energy:
dU  dU  0  dA  dU (2.8.1)

Therefore, let us consider such two cases:

1. Expansion

Under the conditions of expansion (fig. 2.8.1) the volume of system
increases dV   0 and work done by

expansion is positive dA   0 ,
then internal energy of system

decreases and as result of such
expansion temperature of system
reduces. Such phenomenon is called

adiabatic cooling.
Figure 2.8.1
2. Compression

Under the conditions of compression (fig. 2.8.2) volume of the

system decreases dV   0 and work done by expansion is negative

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