problem $7?$ In civil engineering, theoretical frameworks underpin the understanding and application of various principles. These theories encompass structural analysis, material science, fluid dynamics, and geotechnical engineering, among others. For instance, structural engineering relies on theories like Euler$-$Bernoulli beam theory or plasticity theory to predict behavior under different loads. Fluid mechanics employs Bernoulli's principle and Navier$-$Stokes equations for flow analysis. Geotechnical engineering applies principles of soil mechanics and elasticity theory to assess soil behavior. These theoretical bases guide engineers in designing safe, efficient structures and infrastructure. Understanding theoretical underpinnings is crucial for solving complex engineering problems and advancing the field.