# Re: Propellant fluid dynamics at zero-g

• Subject: Re: [amsat-bb] Propellant fluid dynamics at zero-g
• From: "Richard D. Burgan" <wc8j@xxxxxxxx>
• Date: Wed, 10 Jan 2001 21:20:12 -0500

Hi All,

I don't believe in centripetal or centrifugal force.  Any good Physics text will
give the arguments more clearly than I intend to here.  To prove it one way or
the other try this experiment:  While whirling a ball (or other small mass) on a
string around you.  Let go of the string.  Which way does the ball go?  Don't do
this in a china shop!

73's de Rich @ WC8J

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Tony Langdon wrote:

> > > ... though I hate the term centrifugal force... but anyway . . .
> >
> > My wife (teaches physics) insists on the "centripital force"
> > (which is the
> > correct term for the restraining "force"), but it just don't convey
> > the meaning of things "flying" outward.
>
> Centripetal force is a real force.  it is the force that pulls an object in
> a curved path towards the centre of the curve.  For example, if you swing a
> rock in a circle over your head, the centripetal force is provided by the
> string (unless it breaks! :) ).  With a satellite, the force is provided by
> gravity.  With a spinning satellite, centripetal force comes from the
> satellit's own frame (that's what stops it flying apart when it spins!).
>
> Centrifugal force isn't a real force, but a "reaction force" caused by the
> inwards acceleration of the centripetal force.  Much like weight is caused
> by the reaction of the ground against our bodies which are being pulled into
> the Earth by gravity...
>
> > So in a compromise to save our marriage, I now only use the term
> > "centrifugal effect"...  and have achieved peace in the household...
>
> Hehe, cute. :-)
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