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Re: [Phys-l] mass and the ring down (free decay) of a pendulum

On 06/09/2007 02:52 PM, Bernard Cleyet wrote:

For linear damping the decay constant is independent of the mass. [1]

Well, I suppose you could define "linear" damping so as to
make assertion [1] reliably true ... but if you do that,
how do you know that the /actual/ damping complies with
this rather narrow restriction?

I can think of lots and lots of physically-plausible
damping processes that do not lead to decay independent
of mass. For example, most kinds of fluid-dynamical
drag will produce a /force/ dependent on the shape of the
object, independent of mass to a more-than-good-enough
approximation, leading to a strong mass dependence in
both the Q and the ring-down time.

When all else fails, think about the physics. What is the
physics that sets the resonant frequency? What is the physics
that provides the damping?