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Re: Choosing Coordinate Systems



This is partly to echo what has already been said, but to add slightly
different wording.

I agree it usually leads to simpler math if we choose one of the axes
parallel to the acceleration. But what if there isn't any acceleration or
motion?"

Therefore, I say... It usually leads to simpler math if you align one axis
with the motion or the intended motion. Then I give some examples when
appropriate. Examples: If I am trying to pull a sled using a rope, the
intended motion is along the ground; not in the direction I am pulling with
the rope. If I am trying to push a box up a ramp, the intended motion is
parallel to the ramp. On a banked highway, the intended motion is not
up/down the incline, it is toward the center of curvature.

Of course things do not always go where we intend them to go... but I think
this wording reaches a few more students than saying "parallel to the
acceleration."


Michael D. Edmiston, Ph.D. Phone/voice-mail: 419-358-3270
Professor of Chemistry & Physics FAX: 419-358-3323
Chairman, Science Department E-Mail edmiston@bluffton.edu
Bluffton College
280 West College Avenue
Bluffton, OH 45817