Chronology Current Month Current Thread Current Date
[Year List] [Month List (current year)] [Date Index] [Thread Index] [Thread Prev] [Thread Next] [Date Prev] [Date Next]

Re: little gee and its sign



John Decker Wrote:

...

At 02:55 PM 9/10/01 -0500, Herb Schulz wrote:
I've
always taken points away from students that don't define the
coordinate system they are using in a given problem;

I agree that students should be taught to think clearly and communicate
clearly about their choice of coordinate system.

On the other hand, I think the foregoing overstates it a bit. Any
physically-significant calculation will give a final result that is
!independent! of the choice of coordinate system -- so if only the final
result is being presented, there is no reason why anything needs to be said
about the coordinate system.

In any case: Students should not be required to guess what coordinate
system the teacher would have used, nor penalized for choosing a different
one.


Howdy,

That is not completely true. E.g., depending upon the chosen
coordinate system the calculated x-position of an object at a certain
moment in time might be +23.5m in one coordinate system while it is
-4.7m in another coordinate system; the Physical Position is the same
in both cases (as you implied) but the Numbers used to Describe that
x-position depend upon the coordinate system chosen and you must know
that coordinate system for the numbers to have Physical Meaning.

Good Luck,
--
Herb Schulz
(herbs@interaccess.com)