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MDCAT Physics QUESTION #4415
Question 1
According to the First Law of Thermodynamics, when heat flows into a system and no work is done, the internal energy of the system must:
  • Increase✔️
  • Decrease
  • Remain constant
  • Become zero
Correct Answer Explanation
First Law of Thermodynamics: $\Delta U = Q - W$. If heat $Q$ flows into the system ($Q > 0$) and no work is done ($W = 0$): $\Delta U = Q - 0 = Q > 0$. The internal energy increases.