Question Detail
Question
If a system absorbs 50 kJ of heat and does 30 kJ of work on the surroundings, what is the change in internal energy (ΔU)?
Correct Answer
Option B is the correct answer.
Detailed Explanation
ΔU = q + w. q = +50 kJ (heat absorbed), w = -30 kJ (work done by system). ΔU = 50 + (-30) = +20 kJ.
Hint
Use the sign convention: heat absorbed is positive, work done on the system is positive.