Re: [Phys-l] neat video of synchronizing metronomes

[Bernard Cleyet <bernardcleyet@redshift.com>]

On 2011, Jul 21, , at 12:34, John Denker wrote:

> A good pendulum clock has a much higher Q than an ordinary
> metronome.  You can hang cuckoo clocks on the walls in
> different rooms, even rather far apart in a large house,
> and they will phase lock, assuming you tune things properly, 
> and assuming the clocks are well made.  It's kinda spectacular 
> to hear the cuckoos /precisely/ in synchrony, hour after hour, 
> day after day.


Huygens originally believed the synchronization was due to air currents shared between the two pendulums, but he dismissed the hypothesis himself after several tests. Huygens would later attribute sympathetic motion of pendulums to imperceptible movement in the beam from which both pendulums are suspended. This idea was later validated by researchers from the Georgia Institute of Technology who tested Huygens' idea.[4]

http://en.wikipedia.org/wiki/Odd_sympathy

A modern repetition:

http://www.bmumford.com/clocks/tech/2clocks/2clocks.html


JD's link is the one discussed at length a few years ago on tap-l.  That prompted me to purchase several Super Mini Tactells, a mini high ratio bob mass to support (case, etc.) metronome. 

http://www.allegrotuning.com/piano-accessories/index.php?main_page=product_info&cPath=3&products_id=8

 Others don't work well, if at all.  I glued one to a pendulum to explore a driven double pendulum, à la the swinging clock.

http://labbcoco.en.made-in-china.com/product/eqiEHVaOhAUX/China-Swinging-Clock-JG5032A-.html

Instructive is to explain why the synchronization is only one mode.  Tho I notice that the left most metronome is for a short time in antiphase to the others.  I succeeded w/ difficulty obtaining both normal modes using two Tacktells.

bc  still kicking himself for not returning to purchase a large one at a Carmel antique store.