From: poutnik4REMOVEnntp@CAPITALSgmail.com
John Heath Wrote in message:
> On Monday, February 26, 2018 at 10:33:11 AM UTC-5, Jonathan Thornburg
[remove -animal to reply] wrote:
>> John Heath wrote:
>>> when it comes to spinning a box from
>>> within it seems nature will look the other way if a bribe in the
>>> currency of energy is payed. Apparently the universe does not feel a
>>> need to spin counter clockwise if a box is spinning clockwise.
>>
>> That's not true. Let's pick a fixed spin axis (fixed in an inertial
>> reference frame) about which to compute angular momentum. Among the
>> consequences of conservation of angular momentum are:
>> (a) If we spin up a box in the clockwise direction (about our spin
>> axis) then we must indeed spin up the rest of the universe in
>> the counterclockwise direction (about that same spin axis) so
>> as to keep the net angular momentum of the universe (about that
>> spin axis) constant.
>> (b) If no torques are exerted on a sealed box (i.e., no angular
>> momentum flows in or out through its walls), then the box's
>> angular momentum (about our spin axis) will remain constant,
>> regardless of what happens inside the box.
>>
>> Note, however, that (b) does NOT imply that the box/s angular
>> ORIENTATION will remain constant. For example, a free-falling cat
>> may turn her body from upside-down to right-side-up without exerting
>> any torques on the box or the outside world.
>>
>> I'll say more about this latter example in a following post.
>>
>> --
>> -- "Jonathan Thornburg [remove -animal to reply]"
>> Dept of Astronomy & IUCSS, Indiana University, Bloomington, Indiana, USA
>> currently visiting Max-Plack-Institute fuer Gravitationsphysik
>> (Albert-Einstein-Institut), Potsdam-Golm, Germany
>> "There was of course no way of knowing whether you were being watched
>> at any given moment. How often, or on what system, the Thought Police
>> plugged in on any individual wire was guesswork. It was even
conceivable
>> that they watched everybody all the time." -- George Orwell, "1984"
>
> Fair enough. I will do my best to put you in check mate with regards to
> angular momentum by bribing nature with a little energy under the table.
>
> You are in a box in space and both yourself and the box are not rotating
> relative to the stars that can be seem out the window. You now step on a
> turn table spin yourself clock wise CW. This causes the box to turn
> counter clock wise , CCW . You are turning CW and the box CCW. Angular
> momentum has been conserved. I will ask you to put an elastic band
> between your thumbs then allow your hands to spread out caused by your
> CW spin. Lock the elastic band in the stretched position. Check mate as
> you just bribed nature with the currency of energy , stretched elastic
> band. As you were on a turn table when you did this the spinning of the
> box was not effected. As long as you have a locked stretched elastic
> band in your hand the total angular momentum of yourself and the box can
> not be restored to zero without violating energy conservation laws.
>
> I have an open mind to a counter argument.
>
The extra energy conserved in the fixed stretched rubber band is
covered by the extra spent chemical energy of ATP in the body
muscles.
Or, in case of some engine instead of an acting biological body,
by extra spent engine energy.
So there is no energy violation. Higher energy of rubber is
compensated by lower energy of the energy source.
--
Libor Striz aka Poutnik ( a pilgrim/wanderer/wayfarer)
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