Definition
Thermodynamics is the branch of physics that deals with heat, work, and temperature, and their relation to energy, radiation, and physical properties of matter.
- How to read: “dU equals dQ minus dW.”
- Meaning: First Law of Thermodynamics in differential form. A system’s internal energy change equals heat added minus work done by the system.
Why It Matters
The laws of thermodynamics are the ‘unbreakable’ rules of the universe. They define the limits of what is physically possible, from the efficiency of an engine to the ultimate fate of the cosmos (entropy), providing the ultimate first-principles boundary for all engineering.
Core Concepts
- Zeroth Law: Establishes the transitive nature of thermal equilibrium.
- First Law: Conservation of energy; energy cannot be created or destroyed.
- Second Law: Entropy of an isolated system always increases; heat cannot spontaneously flow from cold to hot.
- Third Law: As temperature approaches absolute zero, the entropy of a system approaches a constant minimum.