218 
Sec. 4 Jr Eq. 16-19 
Here a is the velocity of ordinary sound in the original medium, and 
y= ices the ratio of the specific heats at constant pressure and volume, 
This expression reduces to D=a for w=0, as it should, and to 
Dos (1+ y)w (16 
for w large. Furthermore, accurately, 
Pp - Py = Dw/V, , (17 
(Vo/V;) =1- (w/D) ESS (¥-1)/( 7+ 1), (18) 
and To = Ty = 4 [ (Po + P1)/ (25 es P)) | w" [ey . (19 
The table shows the results of some calculations for shock waves in 
, based on these equations, Here a = 53.4 10' om./sec., y = ile 
Vi = 380 ec. per gram, Cc, = 0.9 x 10! erss/g./deg., R/M = 2.87 x 10 
ergs /deg. /gram, PL =e eur, 
w/a = 0.5 1 5 10 20 
D/a = oe Le fend Golke 12h 2h, 
Po = 1.87 Bo | a 158 625 atm. 
AYRE) = 0.65 O.44 0.19 0.17 167 
f= Tye 53° 120° 1720°  6500° 25600° Cc. 
These results are obviously only illustrative, since the variation of 
specific heat with temperature should be taken into account. They do, 
however, show that very high temperatures and velocities are accompanied 
by relatively low pressures, which is in agreement with the fact that shock 
waves in air are not particularly destructive comnared with similar waves 
in water. 
More accurate results for air are given in Sec. 16a where the variation 
of Specific heat is taken into account. 
