Thermodynamics #
Thermodynamics studies how heat and work interact. It governs everything from car engines to refrigerators to power plants.
The Laws #
- Zeroth Law: if A is in thermal equilibrium with B, and B with C, then A is in equilibrium with C (defines temperature)
- First Law (energy conservation): \(\Delta U = Q - W\) — energy can’t be created or destroyed
- Second Law: heat flows spontaneously only from hot to cold. Entropy always increases.
- Third Law: absolute zero (0 K = -273.15°C) can never be reached
The Carnot Cycle #
The most efficient theoretical thermal cycle: two isotherms + two adiabatics.
$$\eta_{Carnot} = 1 - \frac{T_{cold}}{T_{hot}}$$No real engine can be more efficient than a Carnot engine.
Applications #
Internal combustion engines, steam turbines, power plants, refrigerators, heat pumps.
Conclusion #
Thermodynamics sets the fundamental limits on energy conversion. Understanding it is essential for designing efficient machines and sustainable energy systems.
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