"In this chapter we will show how to apply eenrgy methods to solve problems involving deflection. The chapter begins with a discussion of work and strain energy followed by a developmentn of the principle of conservation of energy. Using this principle, the stress and deflection of a member are determined when the member is subjected to impact. The method of virtual work and castiigliano's theorem are then developed, and these methods are used to determine the displacement and slope at points on structural members and mechanical elements."