=+describing the equilibrium in the bar for a harmonic motion, when no volume forces are present. This equation is identical to the free vibration equation (4.129), but now we consider nonhomogeneous boundary conditions in order to obtain the impedance matrix between the end displacements qT = [

u1, u2

]

and the end loads pT = [

N1 N2

]

in the form:

Z(????)q = p (P4.3.b)

where ???? = ω2ml2