Thermodynamic Systems Answer Check.

[keith river]

Question : State which type of thermodynamic system (Isolated, Closed, Open) the following are... Include in your answer which type of system they are relative to short and long time periods.
A list then followed.

I'm unsure about only one.
A thermal flask.

I know in the long term a thermal flask is a closed system (EG, after about a day or so hot tea would be cold) but in the short term I'd say a thermal flask is an isolated system (the tea doesn't leave nor does the heat)

But I know the only real isolated system is the entire universe so I'm unsure if this is an acceptable answer or not. What do you all think?

[Redbelly98]

Question : State which type of thermodynamic system (Isolated, Closed, Open) the following are... Include in your answer which type of system they are relative to short and long time periods.
A list then followed.

I'm unsure about only one.
A thermal flask.

I know in the long term a thermal flask is a closed system (EG, after about a day or so hot tea would be cold) but in the short term I'd say a thermal flask is an isolated system (the tea doesn't leave nor does the heat)

But I know the only real isolated system is the entire universe so I'm unsure if this is an acceptable answer or not. What do you all think?
I'm not 100% sure, because of the very reasons you gave, but ... I'm inclined to think they mean an ideal, perfectly insulated flask.

After giving your answer on your homework paper, you could add a remark along the lines of "However, a REAL flask would be ______."