On 7/27/2016 10:04 AM, time-nuts-request@febo.com wrote:

Sure you can. Spin it at 100 RPM, or 1000, RPM or even 25000  RPM... :)

Interesting conversation. I tend to agree the earth is not a classic
harmonic oscillator. Energy is not exchanged between different storage
mechanisms. It's rotational period has no natural harmonic frequency.
i.e. rotational period could be anything.

However I also agree it exhibits characteristics of other items that Q
can be calculated for. Rate of slowing, loss of energy per cycle, etc.
And since the definition of Q is varied and used quite widely, it seems
Q is also appropriate here.

Maybe Earth is a special case since after all it DID give us the second,
and we DO set our atomic clocks to IT every 6 to 12 months...

...now I'll be thinking of this all night...  ...I think Tom is just
toying with us now...

Dan

in case the Earth, the circular frequency of the Earth is equal of a
sinusoidal wave's frequency, which is a projection of the Earth circular
movement in a plain, which is perpendicular to the axis of the Earth.
The Q of the Earth in interpreted as the quotient of the phase speed of
the  Earth's  circular rotation [or the projected wave's] and the
fluctuation of the phase speed.

73
KJ6UHN
Alex

On 7/27/2016 8:10 PM, Neville Michie wrote:

Neville Michie namichie@gmail.com wrote:

I don't think it does have a resonant frequency, any more than the Earth
does: the angular velocity of the pendulum is sqrt(g/h) where h is the
height of the pendulum; give it more energy, it swings higher, so h is
smaller, so the frequency is higher.

Tony.

f.anthony.n.finch  dot@dotat.at  http://dotat.at/  -  I xn--zr8h punycode
South Thames, Dover: Southwesterly 5 or 6. Slight or moderate. Rain or
showers. Good, occasionally poor.

Hi All,

Tom gave me a nudge to look here - I hadn't been following this thread.

For those that don't know, I study pulsars and so the way we measure what
pulsars do could be relevant to this discussion.

First, I have never heard of a Q measure when referencing a pulsar. I think
the key here is that it's not resonating as such. Rotating yes, resonating
no.

Pulsars spin and slow down due to giving off energy (magnetic dipole
radiation). So in the pulsar world we mainly refer to spin frequency (F0)
and frequency derivative (F1). With some of the younger and more "erratic"
pulsars, F2 (and further) can be modelled.

Here's some data on the Vela pulsar (hot off the presses - measured just
now):

F0              11.1867488542579
F1              -1.55859177352837e-11
F2              1.23776878287221e-21

Vela is young and erratic. Millisecond pulsars are outstanding clocks.
Here's the data for J0437-4715 - one of the most stable pulsars we know
about:

F0              173.6879458121843
F1              -1.728361E-15

I'm sure the "Q" of Vela would be pretty decent - but I can tell you now,
as a time-keeper, she's useless.

Jim Palfreyman

On 28 July 2016 at 20:50, Tony Finch dot@dotat.at wrote:

What about an ADEV/TDEV plot of the pulsar J0437-4715?

On Fri, Jul 29, 2016 at 12:39 AM, Jim Palfreyman jim77742@gmail.com wrote:

On Wed, 27 Jul 2016 15:15:48 -0400, you wrote:

Capacitors and inductors have an associated Q while lacking a resonate
frequency except for parasitic elements.  Their Q increases with
frequency up to a point; does that apply to a spinning body?  I guess
it depends on the loss mechanism.

If you used the Earth's rotation as part of a harmonic oscillator,
what would limit the Q?  All the sloshing fluid, physical
displacement, and mechanical hysteresis add up to energy lost per
cycle.

This seems like one of those fun physics problems where you start with
a bunch of seemingly unrelated pieces of numerical data and calculate
the mass of the Milky Way.

On Fri, 29 Jul 2016 03:29:27 -0500
David davidwhess@gmail.com wrote:

The Q of an inductor (or capacitor) is defined at a specific frequency.
You can see it as the Q factor that would be achieved, if the inductor
(capacitor) would be paired up with an ideal capacitor (inductor) with
a value such, that it would result in the specified frequency.

Hence, if you increase the frequency, the Q factor increases for an inductor. Conversly, the Q factor of an capacitor decreases with increasing  frequency.

See also:
https://en.wikipedia.org/wiki/Inductor#Q_factor
https://en.wikipedia.org/wiki/Capacitor#Q_factor

		Attila Kinali

--
It is upon moral qualities that a society is ultimately founded. All
the prosperity and technological sophistication in the world is of no
use without that foundation.
-- Miss Matheson, The Diamond Age, Neil Stephenson

the Q factor could be derived from the modulation bandwidth of an
oscillator [ the "old way" of measuring the Q of resonator of the
running oscillator's ], therefore if we look the fluctuation spectrum of
the frequency of an oscillator we could determine the Q. Any circular
movement could be seen as the source of a harmonic oscillation.

73
KJ6UHN
Alex

On 7/29/2016 9:28 AM, Attila Kinali wrote:

Very boring. It's a straight line from top left to bottom right. :-)

See page 5 of this: http://arxiv.org/pdf/1004.0115.pdf

Jim Palfreyman

On 29 July 2016 at 17:33, Azelio Boriani azelio.boriani@gmail.com wrote: