Re: [Phys-l] inertial +- gravitational mass

[Hugh Haskell <hhaskell@mindspring.com>]

At 13:06  -0500 11/20/06, John Denker wrote:
> 2) The question arises whether the inertial/gravitational distinction
>  should be emphasized in intro physics courses.
>
>  I say no.  There isn't enough time in the day for everybody to question
>  everything.  IMHO it would make /more/ sense to do away with [2] and [3]
>  than to do away with [1] in an introductory class.  That is, it would
>  make more sense to do away with F=ma and use fully-relativistic dynamics,
>  and do away with F=GmM/r^2 and use general relativity instead ... while
>  leaving questions about the equivalence principle for another day.
I think I have to disagree here. I do agree that we cannot question 
everything, but we do owe it to the students to understand that there 
*are* deep philosophical questions even in something so elementary as 
the meaning of g, and although they may not be able to fathom the 
answers to these questions, such as they may be, but at least they 
can, even in their state of relative ignorance, appreciate what they 
are, and more important, that they exist, and that physics, even at 
the introductory level, is not a closed subject.

I don't spend a whole lot of time on this particular issue in 
class--perhaps half a period--but it does open the door to raising 
other issues, and in this particular case, it allows the introduction 
of a new idea--the formal definition of a field--in a relatively 
non-threatening context, so that when it comes up again in 
electricity, the idea is not so novel that they are uncomfortable 
with it, and they are at least a little prepared for the additional 
complexity introduced by the fact that electrical mass is not the 
same as inertial mass.

Hugh
--

************************************************************
Hugh Haskell
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<mailto:hhaskell@mindspring.com>

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When you are arguing with a stupid person, it is a good idea to make sure that
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					Anonymous