A system does 500 J of work and loses 200 J of heat. What is the change in its internal energy?
Q1. A system does 500 J of work and loses 200 J of heat. What is the change in its internal energy?
Answer: -700 J
Explanation: ΔU = Q - W = -200 J - 500 J = -700 J. Other options misapply the first law of thermodynamics.