Re: The sign of g

[Herbert H Gottlieb <herbgottlieb@JUNO.COM>]

On Tue, 03 Sep 2002 13:59:17 -0500 Tina Fanetti
<FanettT@QUEST.WITCC.CC.IA.US> writes:

> How do I explain to a student that when we choose up (+y) to be
> increasing, we say that the sign of g is negative, regardless of
whether
> the ball is going up or going down.

*** ...also....remember that the acceleration of gravity is NOT
constant when an object is in free-fall vertical motion.  Although
the changes in acceleration are rather small within a few meters
above the surface of the earth, there is a measurable change
in the acceleration of gravity.

*** also, ..., also ...., regardless of the direction that an object is
moving above the earth's centar of mass, the force of gravity,
and thus the acceleration of gravity on the object, is always downward.

Herb Gottlieb from New York City
(Where the force of gravity is rarely directed upward.and
away from the earth's surface)