Re: Derive energy from angular KE of earth?

[fred bucheit <fbucheit@HOTMAIL.COM>]

Well, it is true that spinning up the flywheel will transfer angular
momentum to the earth, but after that, if the bearings are really good,
there will be a very small amount of angular momentum transferred between
the wheel and the earth.

Fred Bucheit

> From: Brian Whatcott <betwys1@SBCGLOBAL.NET>
>
> How about treating the angular momentum as a storage method.
> Spin up a flywheel, and the Earth takes up a complementary
>   momentum (if you must...)
>
> Brian
>
> At 10:01 PM 12/22/2003, you wrote:
> >[This was brought up on PHYSHARE-L as well, and I still don't get how
> >rotational momentum is conserved. I realize that when I fully understand
> >it, I am going to feel like an idiot, but here goes....]
> >
> >If the energy that is used to light the bulbs, etc., comes from the
> >earth's rotation, then the earth needs to lose kinetic energy. KE of a
> >rotating body is KE = 1/2 (rotational inertia) (rotational velocity)^2. I
> >presume that the actual shape of the earth doesn't change, so its
> >rotational inertia remains constant. That means that rotational velocity
> >must decrease.
> >
> >On the other hand rotational  momentum = rotational inertia x rotational
> >velocity . If rotational inertia stays the same and rotational velocity
> >decreases, then rotational momentum must get smaller. If rotational
> >momentum of the earth gets smaller, then the L of something else must get
> >larger.
> >
> >So, the rotational momentum of what gets larger?
> >
> >Marc "Zeke" Kossover
> >The Hockaday School
>
>
> Brian Whatcott    Altus OK    Eureka!

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