Suppose now that we wish to drive the mass along a frictionless
surface using a variable force
. This is similar to the
previous example, except that we now want the traveling-wave
components of the force on the mass to sum to
instead of 0
:
Since
The simplified form in Fig.F.11b can be interpreted as a wave
digital spring with applied force
delivered from an infinite
source impedance. That is, when the applied force goes to zero, the
termination remains rigid at the current displacement.