Re: free-body diagrams

["JACK L. URETSKY (C)1998; HEP DIVISION, ARGONNE NATIONAL LAB ARGONNE, IL 60439" <JLU@HEP.ANL.GOV>]

Hi all-
        Is this going to be an infinite regression?  Bob Sciamanda writes:
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> This is where most texts stop.  I've now taken to at least mentioning
that
> there is another force, the force of gravity of m_2 pulling up on m_1.
> *********************
>         Say what?
>         As I understand it, m_2 is on top of m_1 and you are doing a
> free-body diagram of m_1.  That diagram shows only forces acting on m_1.
> You are addressing a force acting on m_2, which does not belong in this
> free-body diagram, if it exists.
>         Shame on the people who have already given thoughtless answers.
>                                         Regards,
>                                                 Jack

Say what what?
The gravitational force of m2 acting on m1 is exactly what the man is
talking about!  Check it again, Jack!
Shame on whom?  (   not even an :)   )
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        You've lost me.  How does m_2, which is lying upon m_1, pull upward?
        Comes the dawn.  Are we talking about the gravitational attraction
between m1 and m2?  My goodness!  No shame is ascribed to any party.
                                        Regards,
                                                Jack


        "I scored the next great triumph for science myself,
to wit, how the milk gets into the cow.  Both of us
had marveled over that mystery a long time.  We had
followed the cows around for years - that is, in the
daytime - but had never caught them drinking fluid of
that color."
                Mark Twain, Extract from Eve's
                Autobiography