Partial differential equations (PDEs) play a central role in modern physics as a tool to model fundamental physical processes. This book, the second of a two-volume set, provides a bridge between the problems addressed by physics and the mathematical tools used to solve them. Topics covered in Volume II include thermoelasticity, viscoelasticity, gas kinetics, relativistic fluid dynamics and quantum mechanics. As in Volume 1, the authors describe the connection between various physical disciplines and their related mathematical models, which are described by PDEs. This is followed by in-depth explanations of how PDEs work as mathematical tools to express the basic concepts of physics. The book describes the features of these PDEs, including the types and characteristics of the equations, the behaviour of solutions, and common approaches for solving PDEs. The chapters, which include exercises, are self-contained and are accessible to anyone with knowledge of basic undergraduate maths and physics.