Re: The sign of g

[Jack Uretsky <jlu@HEP.ANL.GOV>]

Good question!  It tickles the thought process, instead of simply
reiterating the same dogma in different languages.

I think that the first difficulty is in understanding the concept:
acceleration.  I suggest that's where the initial focus should be, not in
paper and pencil terms, but in kinesthetic terms.  When you are thrown
forward in your car, the acceleration in backward.  This happens in two
circumstances:  one, when braking; and two, when speeding up in a backward
direction.

This point can really be brought home in the sonic ranger lab where the
student is asked to duplicate a given acceleration pattern.  Try it
yourself, it's a real whoop-de-doo.
                                        Regards,
                                                Jack


On Tue, 3 Sep 2002, Tina Fanetti wrote:

> One thing I think conveyed to them that acceleration is still acting =
> at the top of the balls flight is that I asked them why would gravity=
>  suddenly turn off for this ball at the top? =20
> Tina
>
> Tina Fanetti
> Physics Instructor
> Western Iowa Technical Community College
> 4647 Stone Ave
> Sioux City IA 51102
> 712-274-8733 ext 1429

--
        "What did Barrow's lectures contain?  Bourbaki writes with some
scorn that in his book in a hundred pages of the text there are about 180
drawings.  (Concerning Bourbaki's books it can be said that in a thousand
pages there is not one drawing, and it is not at all clear which is
worse.)"
                                        V. I. Arnol'd in
                                Huygens & Barrow, Newton & Hooke