Partially Emptying a Tank Containing an Ideal Gas

[orangbulu]

HI i need help for one of my homework problems.

http://img141.imageshack.us/img141/290/sp3220080229004426gf6.gif

 

[confuted]

I'll give you a small hint: the phrase "the gas quickly escapes" implies that the process is adiabatic - that is, no heat is exchanged between the system and the environment.

What have you done on the problem so far?