Hi Bill
The easiest way to see what happens is to draw a diagram
and show all the forces at their location on the beam.
Then do a balance equation to see how the forces interact for
the initial conditions.
If the beam is stiff to the point of no flexure then the pivot
absorbs all the force generated. Stored energy device is not
activated, nothing to store.
If the beam is flexible then it would vibrate when the masses
first hit it and the vibrations would dampen out based on the combined
mass of weights and beam on the pivot point.
If you then considered the spring/stored energy component attached at
one end of the beam then it would change the vibration response of the
beam and mass. This means both the initial impulse and the subsequent
vibrations dampening out.
The extra stored energy device makes the analysis more complex as the
vibrations would travel back and forth in the beam-mass assembly.
An then to make it more interesting you can make each item a system
with its own frequency response characteristics and play around
with the interactions to achieve a lasting resonance to get the most
out of dropping the weights.
Check out HighText Publishing Inc. "Modeling Engineering Systems",
by Jack W. Lewis a very cool intro to modeling such questions.
Jim