The way I try to link 1-D to 2-D is by treating the 2-D situation as two
simultaneous 1-D problems. It seems to me that's the way projectile
motion is generally taught. We have a 1-D situation in y with constant
acceleration, and this occurs simultaneously with a 1-D situation in x
with zero acceleration. Perhaps I am fooling myself, but it seems to me
some students visualize this quite well.
Michael D. Edmiston, Ph.D.
Professor of Chemistry and Physics
Bluffton University
Bluffton, OH 45817
(419)-358-3270
edmiston@bluffton.edu
-----Original Message-----
From: phys-l-bounces@carnot.physics.buffalo.edu
[mailto:phys-l-bounces@carnot.physics.buffalo.edu] On Behalf Of John
Clement
Sent: Tuesday, September 09, 2008 2:39 PM
To: 'Forum for Physics Educators'
Subject: Re: [Phys-l] Deceleration or Negative Acceleration
Of course there is nothing wrong with + and - in the 1D situation.
There is the question as to what is the best way to proceed. Should one
start with 2D or 1D? The only book that I have ever seen that makes
this clear is the HS text, Minds on Physics, where they define + and -
in the 1D situation as being direction indicators, and they are very
consistent with the notation.
This text would also be appropriate for a non calculus college course.
I recall there is some research that shows that students poorly link the
1D and 2-3D examples. They treat them as completely separate things.
There is math research that shows the same thing with respect to volume
and area.
One of the McDermott papers may have shown this problem.
Unfortunately things like the Real Time labs are heavily into 1D motion,
but they do ask the appropriate questions to help students clearly
understand the connection between signs, directions, and slowing down or
speeding up.