A system had 150 kJ of work done on it and its internal energy increased by 60 kJ .
How much energy did the system gain or lose as heat?

Question

Quizplus · Accepted Answer

According to the first law of thermodynamics, the change in internal energy of a system (ΔU) is equal to the heat added to the system (Q) plus the work done on the system (W): ΔU = Q + W. In this case, ΔU = 60 kJ and W = 150 kJ. Solving for Q: Q = ΔU - W = 60 kJ - 150 kJ = -90 kJ. The negative sign indicates that the system lost energy as heat, so the best choice is A) The system lost 90 kJ of energy as heat.

A System Had 150 KJ of Work Done on It