Virtual Work II: Equilibrium States and Reaction Forces in Nonrigid Systems

This lecture covers the concept of virtual work in structural mechanics, focusing on equilibrium states and reaction forces in nonrigid systems. The instructor explains the principle of virtual work for external forces and moments, illustrating with examples of car jacks and mechanical systems. Topics include determining equilibrium positions, applying virtual work to external loads, and computing reaction loads in trusses and beams. The lecture also discusses the use of auxiliary coordinates to analyze structures and solve for support reactions. Practical examples and sample problems are provided to demonstrate the application of virtual work principles.