Thermodynamics

The study of heat, work, temperature, and the statistical behavior of multi-particle systems.

The Four Laws

• Zeroth Law: If two systems are in thermal equilibrium with a third, they are in equilibrium with each other.
• First Law: Energy cannot be created or destroyed, only transferred ($\Delta U = Q - W$).
• Second Law: The total entropy of an isolated system can never decrease over time ($\Delta S \ge 0$).
• Third Law: As temperature approaches absolute zero, the entropy of a system approaches a constant minimum.

The Carnot Cycle

The Carnot cycle establishes the maximum possible efficiency of any heat engine operating between two temperatures ($T_H$ and $T_C$).

$$ \eta_{max} = 1 - \frac{T_C}{T_H} $$

Temperatures must be in Kelvin. No real engine can achieve this efficiency due to irreversible processes like friction and imperfect insulation.