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Re: [Phys-l] g...



Hi all-
I think that part of the problem is that we experience the effect of gravity as a force. Teaching is usually easier if we go with the experience. So I would modify Dvid's prescription by speaking of the "force per unit mass" due to gravity. This language recognizes the experiential part and doesn't require that an object be seen to accelerate. So: F/m, not a!
Regards,
Jack



On Sat, 18 Nov 2006, David Ward wrote:

Cliff:

I don't refer to g as the acceleration of gravity. After all, gravity
doesn't accelerate but objects accelerate under the influence of a net
force. I refer to g as the "acceleration due to gravity." Once we really
get heavily into fields (second semester at my school), then we discuss
g as being a force per unit mass and move on to force per unit charge.
In any event, as Arons might caution, the language is quite important.
Acceleration DUE to gravity.

Despite my great clarity :) I usually have a few students who will have
difficulty with g.

Have a great day!

david

David Ward
Professor of Physics
UNU# 3160
Dept. of Physics
Union University
1050 Union University Drive
Jackson, TN 38305-3697
office (731)661-5241
FAX (731)661-5175
dward@uu.edu
"Cliff Parker" <cparker@charter.net> 11/18/06 2:05 PM >>>
I have a problem with g. Despite my best efforts many of my students
still want to say that g is a force. I can see where the whole thing
would be confusing for them. Our first experience with g is to call it
the acceleration of gravity on Earth. I stress over and over that it is
not "gravity", it is not "the force of gravity", it is the acceleration
that objects undergo as they fall to the Earth. However, bout the time
I think that I have that idea pumped into their heads we start using g
to find weights w=mg. Now the object is not accelerating at all so
what's g? I usually only address the idea that g is now being used as a
constant that represents the strength of the gravitational field if one
of my students brings it up, and that's not very often. Maybe that's a
mistake. Now g is appearing once again in Newton's Universal Law of
Gravity this time twice... Fg = G m1 m2 / d^2 I asked my students to
describe what g was on a quiz yesterday and got back answers that
were all over the map. Any advice?

Cliff Parker
Never express yourself more clearly than you can think.
- Niels Bohr
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Forum for Physics Educators
Phys-l@carnot.physics.buffalo.edu
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_______________________________________________
Forum for Physics Educators
Phys-l@carnot.physics.buffalo.edu
https://carnot.physics.buffalo.edu/mailman/listinfo/phys-l


--
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just before leading them into the Little Big Horn Valley