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Question
A system releases 100 kJ of heat while 80 kJ of work is done on the system. Calculate the change in internal energy.
Solution
Q = -100 kJ
W = -80 kJ
Q = ΔU + W
-100 = ΔU - 80
-100 + 80 = ΔU
ΔU = -20 kJ
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