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-----Original Message-----
From: phys-l-bounces@carnot.physics.buffalo.edu
[mailto:phys-l-bounces@carnot.physics.buffalo.edu] On Behalf
Of John Denker
Sent: Friday, December 23, 2011 7:17 PM
To: Forum for Physics Educators
Subject: Re: [Phys-l] What comes first, the equation or the
explanation?
On 12/23/2011 04:52 PM, Bernard Cleyet wrote:
Why does increasing the mass of a harmonically driven, with linear
dissipation at resonance, pendulum's bob reduce the pendulum's
amplitude?
The question has been asked before.
The question is just as nonsensical now as it was then.
I don't care how many calculations are done in how many
references. It's nonsense.
Much depends on /how/ you change the mass. If you change it
in the most natural way, so as to cause minimal disturbance
to the pendulum, there is *no* effect on the amplitude.
Galileo figured this out 400 years ago. Take two pendulums,
side by side, initially connected. At some point, disconnect
them. Now each pendulum has half the mass, the same amplitude,
and the same period as before.
There is no historical evidence that Galileo actually did the
experiment in exactly this form, by dropping pairs of things
at Pisa or anywhere else. There's no reason he should have
done it, because there's no point in doing the experiment if
you already know the answer, which he explicitly did. He
considered it an obvious corollary of the experimental and
theoretical work he had already done.
Re-asking the question is not going to change the answer.
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