1433 
oo ) 
Fee ee za) ee SEE Ta,k (5) 
fo Lo <p 
It further is of general interest to know the speed of a 
shockwave propagating in the medium behind the primary shock. 
Designating the data behind the primary wave with a, , om | b 
etc., and those behind the second wave with & >» Xo > otc., 
the velocity pt of the second wave can be derived: 
ph =a, (1¢ “7 
with 7} as pressure difference between behind and in front of the 
second wave. 
Therefore s 
C/o a 
p} calf + (2u-k) Tf! EC RAE gn ye j 
b CF 77> 
ecause haat = Ne + ee w . Neglecting terms 7/7 we get: 
1 = = /2 ~ ops 7} 
D ay { ets oe da fi a (6) 
aed for tf =e 
ve ~k 7) 
D a, (/ t Of6-kK)D (7) 
Attention is called to the fact that p and a are 
speeds relative to the medium behind the first shockwave. Since 
this medium flows with a velocity u these velocities related 
to the medium in front of the first shockwave are obtained by 
veotorially adding u to pl and a. 
