1308 
(cf. equation (5)). 
Vi =V) =o. aeGP) 
Put f(b) = 0, VF) 
Then V=V, + Pald) (6a 
If the sense of the direction from left to right be always 
positive, the equation (6a) applies to fig. la. Such a forward 
shock=-wave will be designated S. On the other hand, a back- 
ward shock traveling toward the left will be indicated by 5 
and will satisfy the following relation. 
Vv = vit - Pf (P) (6b 
The various shocks that are possible for a given value of V 
or of V, may be conveniently represented on a V,p diagram 
(fig. 4a,b). It is to be noted that if a point k is given 
on a V,p diagram, a single infinity of curves V = V, + Py (BD) 
can be drawn through that point, since F,(P) is a function 
of p and of A, . If A, however, is also fixed, then the 
curve through k is determined. 
Fig. 4 
(0,-P) 
