Are these two equations for adiabatic processes the same

[Rujano]

Hi.

I was just wondering about this because is most texts I've seen this one:

Tf/Ti = (Vi/Vf)^y - 1

y= gamma (Cp/CV)

However, in my worksheets I always see this one:

Tf/Ti = (Vf/Vi)^1 -y

And actually, when I tried to solve one problem, I tried to use the first one but the result wasn't the same...

 

[Andrew Mason]

Hi.

I was just wondering about this because is most texts I've seen this one:

Tf/Ti = (Vi/Vf)^y - 1

y= gamma (Cp/CV)

However, in my worksheets I always see this one:

Tf/Ti = (Vf/Vi)^1 -y

And actually, when I tried to solve one problem, I tried to use the first one but the result wasn't the same...

The two expressions are equivalent:

$$x^y = x^{({-1}*{-y})} = (1/x)^{-y}$$

So I suggest that you go back and check your math again. The result has to be the same.

AM