[Phys-l] Pendulum trivium. Was: Re: Queston: simple pendulum lengthen suspension.

[Bernard Cleyet <bernardcleyet@redshift.com>]

The O Botafumeiro in the Cathedral of Santiago de Compostela (N. Spain) 
is parametrically forced * by tiraboleiros on cue by the verger.  The 
suspension rope (d. = 4.5 cm) is periodically pulled over steel rollers 
(originally wood 12 Cent.?).  The suspension is about 20 m long,  the 
censer's mass 53 kg.  The mass of the rope is so great that the fumeiro 
is a compound pendulum.  It is pumped to an amplitude of ~ 82 deg.,  
spewing incense smoke and fire at 68 km/h max.  It's very noisy too.


*  The Pendulum,  Baker et al.


bc, to add it to his visit to the Cathedral at Pisa.


John Denker wrote:

> On 03/17/2007 05:41 PM, Bernard Cleyet wrote:
>  
>
> > What happens to the amplitude if one suddenly lengthens the suspension 
> > at equilibrium position or at max. displacement?
> >    
>
> That question is just part of a larger topic.  Let me address
> the whole topic, since it is just as easy.  It illustrates the
> grandeur and unity of physics:  A playground swingset is related
> to the foundations of quantum mechanics and to electronic
> measuring instruments.
>
>
>
> The length of a pendulum is considered a /parameter/.  The same
> analysis works for other oscillators (including electrical LC
> oscillators).
>
> By modulating ("pumping") the length (or some similar parameter)
> you can make a /parametric amplifier/.
>
> You don't really want to do it "suddenly" because that would
> break something.  It is conventional and sensible to simplify
>
>  
cut