DOC. 4
KINETIC THEORY LECTURE NOTES
195
Now
we
have
8E
__ _dA8E
EaEdA÷E
=
8k
äp,,
dt
de
+
-de
-
-
9.
=
o
e2
e
Thus,
-
is
a
total differential
e
-
=
-de
+
d
e
=
-c
e
E
ß
-I
-
e e
"ER
S
=
-
-
-c
T
N
Thus,
quantity on right
is equal
to
the
entropy.
We
can
rewrite
this
E
F
_E
lg
J
=
0
c +
lg
je
*dpx
dp
n
=0
Since all
systems practically
the
same
energy,
E
can
be
replaced
in this
equation
by
the
mean
value
E0
°
~
|
+
=
0
Thus also
E+6E
s
-
Q
-
^ig
r ^
dp"(for
=
-ig(G.)
r
JV
J
given
A)
#
Entropy
=
const
•
magnitude
of the
region
of the
elementary
variables
that
belongs
to
E
&
X1
.....
Xn.
dp, dp"
=
1
[p.
46]