Last Minute Lecture

Energy, Work & the First Law Explained | Chapter 19 of University Physics Chapter 19 establishes how heat and work transfer energy into and out of a system and unifies them through the First Law of Thermodynamics. You’ll learn how to track internal energy changes, interpret p–V diagrams, and distinguish the major thermodynamic processes that govern ideal gases. Watch the full video summary here for detailed explanations and examples. Thermodynamic Systems & Processes A thermodynamic system is the specific collection of matter under study, while the surroundings encompass everything else. A thermodynamic process describes how the system’s state variables—temperature (T), pressure (p), volume (V), and internal energy (U)—change when heat or work crosses the boundary. Heat & Work Heat (Q) is energy transferred due to temperature difference: positive when entering the system, negative when leaving. Work (W) is energy transfer via macroscopic forces: positive w...

Thermal Properties of Matter & Kinetic Molecular Theory Explained | Chapter 18 of University Physics Chapter 18 bridges the macroscopic thermal behavior of materials with the microscopic motions of their molecules. In this summary, we explore equations of state for gases, the kinetic-molecular model, molecular speed distributions, heat capacities via equipartition, and phase behavior through phase diagrams and critical points. Equations of State Ideal Gas Law: pV = nRT, relating pressure, volume, temperature, and moles. Alternate form: pV = (m/M)RT to find gas density. Combined Gas Law: (p₁V₁)/T₁ = (p₂V₂)/T₂ for changing conditions. Real gases: Deviate at high pressures/low temperatures; above the critical temperature , liquefaction is impossible. Kinetic-Molecular Model of Gases The model treats molecules as point particles in random, elastic collisions. From collisions against container walls, one derives: pV = (1/3) N m ⟨v²⟩ , linking pressure to ...

Thermal Properties of Materials — Chapter 19 Summary from Callister’s Materials Science and Engineering Chapter 19 of Materials Science and Engineering by William D. Callister, Jr. and David G. Rethwisch explores the fundamental ways materials respond to heat, focusing on critical topics such as heat capacity, thermal expansion, thermal conductivity, and the development of thermal stresses. These properties are crucial for engineering safe, durable, and efficient products across industries. Watch the full podcast-style summary below, and subscribe to Last Minute Lecture for clear, chapter-by-chapter study guides to foundational engineering textbooks! Fundamental Thermal Properties Heat Capacity (C): The quantity of heat required to change a material’s temperature, often measured as specific heat (c) per unit mass. In solids, heat is absorbed mainly through atomic vibrations (phonons), with additional minor contributions from electronic and magnetic effects under cer...