Temperature when a vacuum box is filled with air

[MattConfused?]

Hi everybody,

i am new to Physics Forums and I have a problem that is confusing me. Any help would be much appreciated.

Problem:

A perfectly insulated box has vacuum inside of it (it is evacuated entirely) and is sitting with standard atmospheric surroundings (1 bar, 298K). It is then punctured and fills with air. What is its final temperature?

I am just not really sure how to approach this. The attempts I have made havn't really got me anywhere.

Thanks,

Matt

 

[MattConfused?]

Aaaaand I just solved it...

W = (p1)(V1) = m(Cv)(T2-T1) and (p1)(V1) = mR(T1)

Then solved...