Key Inertia

[Richard Brekne]

I think you are right there Mark... we need a quantity we dont have,,, and perhaps a combination of momentum and energy might do
it. Recall you could get into the same (or similiar) kind of problem with energy as I illustrate with momentum below. (Sarahs
space odessy 2003 with the 1 newton marble and bowling ball)

What we need is something that shows how much inertia is needed AND how much velocity.  Because it seems obvious that a thing
needs enough inertia to overcome the inertia of whatever its asked to move... and at the same time it needs enough velocity to get
the thing moving fast enough. It needs exactly the right amount of each in order to minimize the waste Sarah pointed out... yes ??

Cheers
RicB


Mark Davidson wrote:

> > I'm not sure what you mean here.  Kinetic energy, (mv^2)/2, perhaps
> > differentiates, sort of, I guess, if I understand you correctly.  Only you'd
> > be looking at 2 x 2^2 / 2 being different from 4 * 1^2 / 2, etc.  Is that
> > what you mean?
> >
>
> >RicB wrote:
> >
> >What I am saying is that a 10 pound ball going at 5 m/s is going to have a
> >completly different affect then a 5 pound ball going at 10 m/s tho both have a
> >momentum of 50 momentum units.
>
> I see what you're saying, and the only thing I come up with is the kinetic energies are different (unless V=sqrt(2)).
>
> (Another) Example
> When M=1, V=4, M*V=4 but energy = 8
> When M=2, V=2, M*V=4 but energy = 4
>
> So I guess to capture this you really have to use momentum AND energy, or mass AND velocity.  You're right, momentum by itself
> doesn't capture this.
>
> (You didn't really mix pounds with m/s up there did you? That's almost as
> bad as my 1.75"/10mm blow/dip ratio! :) )
>
> -Mark
>
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--
Richard Brekne
RPT, N.P.T.F.
UiB, Bergen, Norway
mailto:rbrekne@broadpark.no
http://home.broadpark.no/~rbrekne/ricmain.html
http://www.hf.uib.no/grieg/personer/cv_RB.html