Virtual Work II: Conservative Forces and Equilibrium

This lecture delves into the concept of virtual work, focusing on the work done by conservative forces during infinitesimal displacements. Examples of potentials for conservative forces like weight, linear springs, and torsional springs are explored. The principle of virtual work is applied to mechanical systems in equilibrium, illustrating how external forces and moments vanish during virtual displacements. Through examples involving equilibrium positions of mechanical systems with active forces, the lecture demonstrates the determination of equilibrium using virtual displacements and free coordinates. Trigonometry is used to solve equilibrium problems, such as determining the torque needed to maintain equilibrium in a car jack system. The lecture concludes with a discussion on the application of virtual work to calculate internal loads in structures like trusses, beams, and frames.