Chronology Current Month Current Thread Current Date
[Year List] [Month List (current year)] [Date Index] [Thread Index] [Thread Prev] [Thread Next] [Date Prev] [Date Next]

Re: Derive energy from angular KE of earth?



This response sounded confident, but I didn't understand some of
the terms. I will interject with my difficulties of comprehension along the
way.

At 01:14 PM 12/24/2003, you wrote:
Conservation of momentum problems are usually resolved by going back to
Newton's 3rd & identifying which two objects are involved. In this case,
it is the flywheel apparatus and the Earth.

This seems agreeable: To spin up a gyro, the spin up torque is reacted
on something else - let's say the whole rigid Earth.

In the tidal case, is is the
generating station and the ocean. The moon never enters into the system
(except that the moon provides the restoring effect to keep the tides
going)

I wonder if it is generally accepted that the diurnal period grows longer
due in part to tidal friction? The loss of Earth momentum is compensated by
the increasing orbital distance between Earth and Moon?


Does this sound right:

The "Power out" will drive a generator (attached to the Earth) because the
gimbal axis is rotating (with a period of 1 day) relative to the ground.


I find this rotation easy to visualize for a polar situation. The generator
is vertical. The gyro pivots are fixed horizontal by (let's call it) a
C-mount
fixed to the vertical generator shaft at mid-C The shaft evidently turns
once per sidereal day. The comparison with the Foucault pendulum springs
to mind immediately.

(Gyros are usurped by solid state tuning forks in
some applications - and tuning forks are the conceptual offspring of the
pendulum. One could suggest that the tuning fork and the pendulum are
the "Alternating Current" version of the "Direct-current" gyro, in fact).

In order to drive a generator, a torque must be provided by the axle, and
a counter-torque (reaction) applied to the axle in response. Since,
relative to the ground, the axle is rotating with a South-angular-
velocity, the generator will be driven to the South and the gimbal axle
therefore driven to the North.

I don't understand the device to which the word "axle" refers: it could be
the horizontal gyro spindle, or it could be the vertical generator shaft.
I expect this expresses that, in order to turn the generator shaft clockwise
as viewed from above, the horizontal gyro spindle must rotate "clockwise"
as viewed from above.


This torque will be transfered to the flywheel, which will start to move
in that direction. However, it cannot. The gimbal axle will not allow
rotation in that direction.

Let's assume for a moment, wlog, that this takes place on the equator and
the flywheel starts pointing East (a cosmological East, not an Earth-based
rotating East). To prevent rotation to the North-East, the gimbal axle
bearings will apply a downward torque.

I don't understand what downward torque is.

This will also be transfered to
the flywheel, which will start to change its angular velocity "downwards",
causing the gimbal to spin to the North - the same way it was originally
driven by the generator.


I don't understand this description.


The "ultimate" torque will always be perpendicular to the momentum of the
flywheel (try this in other orientations), so the flywheel axis will
continue to spin with a North-velocity.

If "flywheel axis" is the same as "gyro spindle", then I need a definition
of what constitutes a gyro spindle spinning with a "north-velocity"

The original "East" momentum will
be transfered back to the Earth through the gimbal bearings, cyclically -
the flywheel will point East, then down, then West, then up, then East.

The polar gyro points in a sensibly fixed direction of the celestial sphere.
I don't understand the terms "down", "up" in describing a gyro spindle
constrained to remain horizontal.


The end result will be a flywheel that is spinning on a rotating axis, the
direction of that axis will be rotating with a North-angular velocity.
The angular momentum that has been taken out of the Earth is now tied up
in the flywheel-gimbal system, as expected. Unfortunately, that rotation
will lock the generator and gimbal together and there will be no more
source of energy.

Gimbal lock is a well known phenomenon affecting a gyro nested in two
rings. I understood we were to consider a simple C mount fixing
the gyro spindle horizontal?


Once again, it is a case of a differential velocity and two objects being
brought to an intermediate state. The trick is, to figure out how to stop
the spinning, extract the kinetic energy in the process and then restart
the system with flywheel spinning to the East again. If that can be done,
then I think Fred has a winner here. Unfortunately, I fear that doing so
would completely reverse the process, and require just as much energy as
was obtained at the start (ignoring friction).

I don't grasp why a generator shaft should start and stop.

Back to the tides, this is where they differ - the moon restores the tidal
effect for free, we would have to restore the flywheel, and that won't be
free!

What does "restoring a flywheel" mean : does it mean spinning it back up,
when it stops? I understood this was to be a physicist's gyro with
frictionless everything?


On a secondary note, I have no problem at all with the reification of
concepts such as energy and momentum. It is common to refer to energy
being "liberated", "obtained", or "transfered" from one form to another,
for example when wood is burned in a fireplace (ok, "obtained" is pushing
it a little bit!).

The extraction of energy from storage into useful form is similar across a
vast number of processes, the difference lies in the labeling of the
storage "container" - is it labeled bulk kinetic, gravitational potential,
chemical potential, etc.

Similarly, momentum can be "transfered" from one object to another, with
one object "extracting" momentum from, or "yielding" momentum to, the
other.

Reification is the basis of those most valuable conservation principles.
If energy and momentum are not "quantities", then what exactly is being
conserved?


It is a sadness to me that these not unreasonable sentiments cause so much
barracking. If I chose to consider that natural science is a model-making
process with some useful predictive, even explanatory properties, then
I place the alphabetic unknowns of an equation in just the same category
as the Lego pieces that children use for model-building.
To put it even more bluntly: I utterly discount the hierarchical aspect of
conceptualization which places the abstract at some superior level to
the concrete. There is no theory known to physics (at least in my humble view)
which does not posit some material, or model element for any quantity of
interest. Name-calling this process as reification is name-calling the basis
of science. Relations are expressed ALWAYS as quasi-material model elements,
to my mind.





Brian Whatcott Altus OK Eureka!