[yiyo]

I would like to ask in a condition that a perfect gas expands adiabatically against a constant external pressure, if i want to find the final temperature, should i use PV=constant and VT = constant these two formulas?
Is the method same for me to find the final temperature when the perfect gas expands adiabatically and reversibly ? I would like to know if there are any differences between them. Thank you.

[curiouscat]

Is a perfect gas an ideal gas?

[yiyo]

Is a perfect gas an ideal gas?

Yes, it is a perfect gas.

[Borek]

Yes, it is a perfect gas.

I think you've missed the point of the curiuoscat question. "Perfect gas" is not something that has a well known definition. You probably mean http://en.wikipedia.org/wiki/Ideal_gas - and curiouscat was trying to confirm if that's it.

[yiyo]

Yes, it is a perfect gas.

I think you've missed the point of the curiuoscat question. "Perfect gas" is not something that has a well known definition. You probably mean http://en.wikipedia.org/wiki/Ideal_gas - and curiouscat was trying to confirm if that's it.

It is an ideal gas