1295 
Likewise equations (1') and (1") become 
~ 1 os uw! 
M ee: qu us (ay 
and equations (2a') and (2a") give 
o~l sere (1+ §) (2a"! 
Thus for weak shocks Cra) a water=-like substance character- 
ized by the adiabatic equation behaves apparently like an 
ideal gas that would have the same value of the adiabatic 
exponent y 125). (We shall note later that this conclusion 
is not generally valid.) The adjective weak connotes here 
that p 7 (and hence pj» {7 , too). 
We are particularly interested in water. Here the 
parameters take on the following average values 4) in the 
domain of physical interest: 77 = 5,000 atomospheres, b = O, 
and os 7.15. In fig. 2 there is shown a comparison of the 
static adiabatic for these water constants with the rigorous 
Rankine=-Hugoniot curves computed by various individuals 4,5), 
For the purposes of the present discussion it will be adequate 
to use the simple adiabatic as an approximation. It is con= 
venient to introduce two more expressions which are functions 
of the pressure-ratio F and which become for b = 0 
20 te sells 
iceae ge | IVa i 
where 7 represents the velocity of the shock relative to the 
medium in front of it ( T differs from M in the sound- 
velocity that is taken for reference), and 
Sg) Ss 
