Eric;
explain this quote from you, and then we can move on, "Yes, something
has to cause the force, but the force causes the motion. "
What caused that force to push the mouth or hands of the nutcracker
together on the nut? Explain that for me.
Bruce
----- Original Message -----
From: "Eric Fuller" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Saturday, December 18, 2004 10:00 PM
Subject: Re: EVA vs Plastic/Carbon Fibre FFO's: Discuss
> Hi all Bruce wrote;
>
> At 09:31 PM 12/16/2004 -0600, you wrote:
> > There is no force on the nut unless there is force on the lever to
crack
> >the nut, i.e. a force elsewhere effects the force on the nut, whether the
> >hands move or not. I think that is why your example is skewed.
Something
> >somewhere has to cause that channe in force Eric. This is why I get
> >frustrated when someone jumps to kinetics without fully acknowledging
that
> >kinematics must come into play.
>
>
> Bruce are you saying that motion causes the force? I agree that
kinematics
> are intimately related to kinetics. Force causes the motion and not vice
> versa. Yes, something has to cause the force, but the force causes the
> motion. The force can change without there being motion. Take a see saw
> and sit on one side. The force between the underside of your end of the
> see saw and the ground is roughly your body weight. Now place something
> that weighs a quarter of your body weight on the other end of the see
> saw. The force under you end of the see saw is now 3/4 of you body
> weight. There was no change in position, but there was a change in force.
>
> > If a force changed from one test to another, w/ and w/o an orthotic,
> >then some position of bone, or at a joint or joints changed to alter
those
> >forces.
>
> Why? Why does there have to be a change in position for there to have
been
> a change in force?
>
> > And, if the calcaneus or STJ have show no measurable change, for
> >example, then something somewhere else that effects teh calcaneus or STJ
had
> >to have moved or changed position to effect this change in forces.
>
> I still don't see what you mean by my example is skewed.
>
>
> Cheers,
>
> Eric Fuller
>
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