Table of contents

0. Math Review31m
- Math Review
  31m
1. Intro to Physics Units1h 29m
2. 1D Motion / Kinematics3h 56m
3. Vectors2h 43m
4. 2D Kinematics1h 42m
5. Projectile Motion3h 6m
6. Intro to Forces (Dynamics)3h 22m
7. Friction, Inclines, Systems2h 44m
8. Centripetal Forces & Gravitation7h 26m
9. Work & Energy1h 59m
10. Conservation of Energy2h 54m
11. Momentum & Impulse3h 40m
12. Rotational Kinematics2h 59m
13. Rotational Inertia & Energy7h 4m
14. Torque & Rotational Dynamics2h 5m
15. Rotational Equilibrium3h 39m
16. Angular Momentum3h 6m
17. Periodic Motion2h 9m
18. Waves & Sound3h 40m
19. Fluid Mechanics4h 27m
20. Heat and Temperature3h 7m
21. Kinetic Theory of Ideal Gases1h 50m
22. The First Law of Thermodynamics1h 26m
23. The Second Law of Thermodynamics3h 11m
24. Electric Force & Field; Gauss' Law3h 42m
25. Electric Potential1h 51m
26. Capacitors & Dielectrics2h 2m
27. Resistors & DC Circuits3h 8m
28. Magnetic Fields and Forces2h 23m
29. Sources of Magnetic Field2h 30m
30. Induction and Inductance3h 38m
31. Alternating Current2h 37m
32. Electromagnetic Waves2h 14m
33. Geometric Optics2h 57m
34. Wave Optics1h 15m
35. Special Relativity2h 10m

23. The Second Law of Thermodynamics

The Carnot Cycle

Physics

23. The Second Law of Thermodynamics

The Carnot Cycle

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Multiple Choice

Your friend claims they have a design for a reversible heat engine that can operate between the freezing and boiling temperatures of water that has an efficiency of 30%. Is this possible?

Yes

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Verified step by step guidance

Identify the temperatures between which the heat engine operates: the freezing point of water (0°C or 273.15 K) and the boiling point of water (100°C or 373.15 K).

Recall the Carnot efficiency formula for a reversible heat engine, which is the maximum possible efficiency: \( \eta = 1 - \frac{T_c}{T_h} \), where \( T_c \) is the cold reservoir temperature and \( T_h \) is the hot reservoir temperature, both in Kelvin.

Substitute the known temperatures into the Carnot efficiency formula: \( \eta = 1 - \frac{273.15}{373.15} \).

Calculate the theoretical maximum efficiency using the formula. This will give you the Carnot efficiency, which is the upper limit for any reversible heat engine operating between these two temperatures.

Compare the calculated Carnot efficiency with the claimed efficiency of 30%. If the Carnot efficiency is less than 30%, then the claim is impossible according to the second law of thermodynamics.