This lecture by the instructor covers the physical models for micro and nanosystems, focusing on micro- and nanoelectromechanical systems. It delves into the simplest MEMS/NEMS, practical applications like force sensing and mass spectrometry, RF resonators, fabrication sequences, motion detection techniques, and sensitive mass detection using carbon nanotubes. Theoretical background on mechanics, Hooke's law at the nanoscale, types of mechanical responses, linear elastic response, and elastic moduli of materials are also discussed.