Re: The sign of g

[Joseph Bellina <jbellina@SAINTMARYS.EDU>]

I do a similar thing.  I ask them what it means to say the velocity of
something is zero and that the acceleration is also zero.  They conclude
that the object would be stationary, since the velocity is not changing.
Then I ask what would happen to the ball if at the top of its motion
where the velocity is zero, the acceleration wer also zero.  I have them
discussing this questions in pairs, and then ask for vote of what the
ball would do.
In the end the concensus is that the ball would just stay up there, so
it must be that the acceleration can't be zero, since the ball does come
down.

This only works well if you have spent time anchoring the notion that
the acceleration is related to how the velocity changes.

cheers,

joe

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

Joseph J. Bellina, Jr.               574-284-4662
Associate Professor of Physics
Saint Mary's College
Notre Dame, IN 46556