SYMPATHETIC VIBRATION:
This is a phenomena that sounds unbelievable at best, but it does exist and
is a common cause of many clocks stopping. Sympathetic vibration is the transfer of
energy from one object moving with a steady frequency to another object (initially
not moving( connected to it. The objects will transfer energy very
efficently if they are the same length , however , they do not have to
be the same length to transfer energy . A classic example is a large
grandfather clock with a heavy pendulum and a case that
is set up on a rug.When the weights travel downward and get even with the pendulum
bob ,the weights will absorb enough energy from the pendulum to either stop the clock
and or start the weights swinging and stop the clock. Also the clock case can absorb
energy from the pendulum because the case is not solid on the rug. Even the s
lightest instability can cause the clock to stop. On old cases ; if they are loose, if the case is not solid, the pend moving will cause the case to oscillate (this may or may
not be visible) and the case will absorb enough energy to stop the clock. correct
is by securing the case to the wall. be sure the case is solid.
If there are several clocks running on a shelf with similar pendulum
lengths , and the shelf appears solid it still may be possible that the clocks on
this shelf will transfer energy back and forth. The result may not be just stoppage.
One or both of the clocks may not keep time or may be un-regulatable because they
will affect each other.
Sympathetic vibration may be demonstrated by a little device with weights
and strings. Start one weight swinging and very soon the other one will be swinging,
and the first one will be stopped.