6. Why are we interested in the natural frequencies of a structure? How do we find them? 7. In a modal analysis, what is the nodal amplitudes vector? 8. Explain briefly the mode superposition method for doing a transient dynamics analysis 9. When and how do we usually introduce damping into your models? 10. Explain briefly the types of nonlinearities you know 11. Give an example where geometric nonlinearity is important to take into account 12. Explain the simple models of non-linear material behavior we have discussed. What extra material properties are needed?