Page:Chandrasekhar - On the decay of plane shock waves.djvu/29

 Rewriting this in the form

(the + or - sign going respectively with i = 1 or 2) we shall consider the second term in square brackets occurring as the coefficient of dt. We have (cf. eq. (3))

Remembering that θ remains constant during the motion apd using the equations (1) we find that

Thus,

and

Now for a perfect gas (with a ratio of specific heats γ) we have