As we have seen from this lecture, the qualitative nature of the free response of a system will depend on the particular initial conditions given to the system. For example, for a two-DOF system released *from* *rest* (a zero initial velocity for all points in the system):

FIRST MODE |
If the initial conditions are in the first mode
the then response will be HARMONIC having a frequency of the |

SECOND MODE |
If the initial conditions are in the second mode
then the response will be HARMONIC having a frequency of the |

NON-MODAL RESPONSE |
For ANY initial conditions other than those in a) and b), the response will be (generally) NON-HARMONIC and will be a LINEAR COMBINATION of the two modes. |