_Lectures in Physics, Volume I: Classical Mechanics in Substance Applications_ comprises seven modules spread across three parts, structured as an invitation to a discussion on various science topics. The opening part, called a prelude, is dedicated to a thorough description of basic mathematics required in this course such as scalars, geometry, trigonometry, vectors, and rules of their operations. The second part of the text is the theory of classical mechanics focusing on proving, generalizing, and inviting to further discussion the concepts of kinematics, dynamics and statics, and conservation laws by examining displacement, velocity, acceleration, jerk, force, torque, energy, and molecule kinetic theory. The last part deals with classical mechanics applications to substance properties. Readers explore fluids and gases, transfer processes, and the fascinating and at times confusing world of thermodynamics followed by a detailed description of periodic motion. Thorough equations illustrated by figures along with example problems provide students with ample opportunities to discuss course topics in detail and apply what they’ve learned to other courses of their major. _Lectures in Physics, Volume I_ is the first textbook in a two-volume series designed to help students learn and grasp science-related key concepts and applications.