Re: [Phys-l] Weightless

[Rick Tarara <rtarara@saintmarys.edu>]

For the 'apparent weighters' it is the apparent weight that is zero because 
there is no force opposing the gravitational force and it is that opposing 
force (usually the ground or chair) that provides us with the sensation of 
weight. (We might also say that they FEEL weightless.)  I think we would 
reserve 'weightless' for an object in deep outer space, away from any 
massive object.  [Not sure about the zero net gravitational force point 
between the earth and the moon, because one of the complications of this 
approach is that we have to separate Earth weight from Moon weight.  ;-)  ]

Rick

----- Original Message ----- 
From: "John Mallinckrodt" <ajm@csupomona.edu>
To: "Forum for Physics Educators" <phys-l@carnot.physics.buffalo.edu>
Sent: Monday, November 20, 2006 12:21 PM
Subject: Re: [Phys-l] Weightless


> But if an astronaut isn't "weightless," then what is?  Isn't the word
> of absolutely no use if we can't apply it to astronauts?  Weight
> implies "heaviness" and heaviness implies (to me) a tendency to stay
> "pinned by gravity" to some surface.  If a person (or thing?) finds
> that she (or it?) has absolutely no such tendency, then it seems to
> me that she has every right to say that she is "weightless" and that
> we ought to agree with and abide by her assessment.
>
> There's certainly no problem justifying any of this from a Newtonian
> viewpoint.  It's simply a matter of deciding what you want to mean by
> "weight."  I don't see any good reason to require that it mean the
> same thing as "gravitational force."  Indeed, it seems to me a
> genuine disadvantage.
>
> Anthony Lapinski wrote:
>
> > I agree. This is why I discuss bathroom scales and apparent weight. If
> > someone says there is gravity acting on the astronauts AND they are
> > also
> > weightless, it ads to more confusion...
> >
> > [Rick Tarara wrote:]
> > > In the 'g' thread, we've (yet again) opened up the definition of
> > > weight
> > > debate.  While I see certain pedagogical advantages to either of
> > > the two
> > > main approaches, I would ask if the proponents of saying that one IS
> > > weightless while in the space station can explain that from a
> > > Newtonian
> > > viewpoint?  Seems to me that there is only one force acting on the
> > > person.
> > > If we call that the gravitational force due to the earth, then what
> > > (again
> > > in the Newtonian viewpoint) is weight?  Isn't this gravitational
> > > force a
> > > component of your weight?  But it is the only component here in the
> > > Newtonian view and is not zero!
>
> John Mallinckrodt
>
> Professor of Physics, Cal Poly Pomona
> <http://www.csupomona.edu/~ajm>
>
> and
>
> Lead Guitarist, Out-Laws of Physics
> <http://outlawsofphysics.com>
>
>
>
> _______________________________________________
> Forum for Physics Educators
> Phys-l@carnot.physics.buffalo.edu
> https://carnot.physics.buffalo.edu/mailman/listinfo/phys-l