Lecture
This lecture covers the origin and definition of repulsion at short distances due to the Pauli principle, intermolecular interactions, and the role of tension in fluids. It explains the necessity of work to bring molecules to the surface, the behavior of liquid films, and the concept of surface tension. The lecture also discusses the analogy between liquid/gas interfaces and elastic membranes, the experimental determination of surface properties, and the consequences of minimizing surface area in soap bubbles. It concludes with demonstrations of objects floating on water due to surface tension and the movement of soap boats in different liquid environments.