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IB Physics HL B 4 6 Hl Second Law of Thermodynamics Questions

Apply the second law in HL questions about heat engines, refrigerators and irreversible change, tracking entropy and the direction of thermal-energy transfer.

Syllabus
First assessment 2025
Course
Physics HL
Level
HL

Exam points

  • Apply the second law to determine spontaneous heat-flow direction and whether the total entropy of an isolated system increases or stays constant.
  • Explain irreversibility and degraded or waste heat in real processes, including why heat cannot be converted completely into useful work.
  • Analyse entropy changes of the system, surroundings and universe in refrigerators, melting processes and heat-engine cycles, and rule out 100% efficiency.

Learn this topic

Study B.4.6 (HL)—Second law of thermodynamics conceptsOpen the corresponding Concept lesson for explanations, examples and exam connections.

IB Physics HL B 4 6 Hl Second Law of Thermodynamics Questions question 1

[Maximum number: 2]

This question is in two parts. Part 1 is about simple harmonic motion (SHM). Part 2 is about gas in an engine.

Part 1 Simple harmonic motion (SHM)
An object is placed on a frictionless surface. The object is attached by a spring fixed at one end and oscillates at the end of the spring with simple harmonic motion (SHM).

Figure for Question IB Physics HL B 4 6 Hl Second Law of Thermodynamics Questions question 1 — IB Physics HL

The tension F in the spring is given by F=k x where x is the extension of the spring and k is a constant.

The shaded area WXYZ is 610 J . The total thermal energy transferred out of the gas in one cycle is 1.3 kJ .

Explain why the total thermal energy transferred out of the gas is degraded.

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