This lecture covers the physical models for micro and nanosystems, starting with an introduction to modeling general problems in nanomechanics. It then delves into examples such as a cantilevered beam and MEMS devices, exploring the relationship between force and displacement. The instructor demonstrates the use of COMSOL Multiphysics software to analyze structural mechanics, heat transfer, and electrostatics. The lecture also discusses the study of stationary fields, the application of different physics interfaces, and the importance of solid mechanics in structural analysis.