Problems and Solutions on Thermodynamics and Statistical Mechanics

138 Problem8 €4 Solutions on Thermodynamics €4 Statistical Mechanics

Solution:
(a) From the p - V diagram, we can see that the work done by the
working material on the outside world is dW = dpAV in this infinitesimal
Carnot cyce. The heat absorbed in the process is Q = L. The formula for
dW dT
the efficiency of a Carnot engine gives - = -
L T'
Thus - dP = - L
dT TAV'
(b) Since

Hence

Therefore

TO

L Prn

Tm = ( 1+- RTOlnP0)

I L

Fig. 1.38. v

1141

When He3 melts the volume increases. The accompanying plot is a

sketch of the He3 melting curve from 0.02 to 1.2 K. Make a sketch to

show the change in entropy which accompanies melting in this temperature

range.

( wis c 0 nsin)