This lecture covers the fundamental concepts of energy, focusing on kinetic energy and work. It explains how kinetic energy is associated with the motion of an object and how work is done by a force along the direction of displacement. The lecture also introduces the work-kinetic energy theorem, demonstrating how doing work on a system changes its kinetic energy. Various types of forces, including constant and variable forces, are discussed in the context of work done. The path independence of gravity and the distinction between conservative and nonconservative forces are explored. Practical examples and conceptual questions are used to illustrate these concepts.