Answer:
Internal energy decreases
Step-by-step explanation:
According to first law of thermodynamics heat can neither be created nor destroyed , but it changes from one form to another form.
Mathematical representation :
U=Q-w
Where U=Internal energy of system
w=Work done
Q=Heat gain or removed
When system does work then it take positive .When system does work then Q is positive .
Hence, the internal energy will decrease .