Bibliografia: V.Ryan (2002) Structural forces, taken from: http://www.technologystudent.com/forcmom/dkforce1.htm Guana Victor (2010) Esfuerzos estructurales, tomado de: http://es.calameo.com/books/003425082243ce532149e K-12 Outreach Office, Worcester Polytechnic Institute(2013) Fairly Fundamental Facts about Forces and Structure, taken from: https://www.teachengineering.org/lessons/view/wpi_lesson_1