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

[Brian Whatcott <betwys1@sbcglobal.net>]

At 03:41 PM 3/17/2007, you wrote:

> What happens to the amplitude if one suddenly lengthens the suspension
> at equilibrium position or at max. displacement?
>
> bc, puzzled

Sticking to the idea of an oscillator, which constantly switches energy
 between modes: in this case kinetic and potential energy: I see that
  lengthening the pendulum at the center position, while holding its
sidewards kinetic energy constant allows the pendulum's amplitude
to increase, so that it gains the same potential energy as before at
the end of stroke.

If the pendulum's length is increased at the end of stroke, the
ensuing exchange to kinetic energy involves a smaller transaction,
because less potential energy is converted by the reduced drop,
though the former amplitude is maintained.

These model manipulations are simplified by considering that the
 change of length is taken at the pivot.



Brian Whatcott    Altus OK    Eureka!