# When something is cooled, has work been done?

I came across this question, but I dont really understand the answer. Can someone explain it please?

"A gas in a container with a flexible lid is cooled by ice with 250J of energy extracted. Calculate whether the temperature has increased or decreased."

Q = -250 J, W = -250 J, U = 0, no change in temperature

How would I interpret this answer?

Does this mean that the environment has done work on the gas by cooling it (W<0)?

• Where did this question come from and is it the complete question? Jan 17 '17 at 9:40
• @Farcher Jacaranda Physics 1 VCE Units 1 and 2/Dan O'Keeffe, Graeme Lofts, Peter Pentland, Ross Phillips (©John Wiley and Sons Australia, Ltd 2016)-Chapter 1, Q12 B), Pg 19. (It is the complete question)
– user142301
Jan 17 '17 at 23:22

So $250\; \rm J$ of heat is removed from the gas and to keep the internal energy (temperature) of the gas unchanged that loss of heat from the gas must be balanced by $250\; \rm J$ of work done by the surroundings.
With work done by the gas as positive and heat into the gas as positive, using the first law of thermodynamics $\Delta U = \delta Q - \delta W \Rightarrow 0 = -250 - (-250)$ as per the answer.