Re: inertial forces (definition)

[Joel Rauber <Joel_Rauber@SDSTATE.EDU>]

I'm not sure I would make such a bold statement as the one below.  There is,
of course, a difference between whether Isaac would've made the distinction,
say in published and carefully written works; and whether he understood the
difference in the two concepts and might've talked about them over a beer in
a crowded pub with a trusted friend.  Is anyone on the list familiar enough
with  the biographies, e.g. Westerfall's book  (sp ?) to address this
question with some degree of certitude.

Joel
> Isaac himself would not have made the distinction between inertial and
> gravitational mass.  This became most clear when Coulomb's law showed
> that, by analogy, Newtonian gravitation involved a
> "gravitational charge",
> conceptually distinct from the inertial mass in F=ma.
> However, by Newtonian physics we usually mean the consistent
> development
> of Isaac's beginnings by those who developed and extended his ideas
> without contradiction.  Even our wording of Isaac's 3 laws
> clarifies and
> modernizes his statements.
>
> Bob
>
> Bob Sciamanda (W3NLV)
> Physics, Edinboro Univ of PA (em)
> trebor@velocity.net
> http://www.velocity.net/~trebor
>
> ----- Original Message -----
> From: Leigh Palmer <palmer@SFU.CA>
> To: <PHYS-L@lists.nau.edu>
> Sent: Monday, October 18, 1999 8:32 PM
> Subject: Re: inertial forces (definition)
>
>
> > > 3) Newtonian viewpoint says, gravity is not one of these types of
> forces
> > > since the gravitational is proportional to the
> gravitational mass of
> the
> > > object.
> >
> > Was that Newton's viewpoint? Did he distinguish inertial and
> > gravitational mass? He was aware that there is something funny
> > about the gravitational force which seemed to act at a distance.
> > Today we understand that Newton's third law doesn't hold for
> > gravitational forces. (There is no body on which you exert a
> > force which is equal in magnitude and opposite in direction to
> > the force of gravity which acts on you, even on a nonspinning
> > planet.) One must inject the intermediary of a field (which is
> > not a body) to save a semblance the appearances. Newton coined
> > the word "centrifugal" to describe a similar force. I don't
> > believe he ever called it an inertial force.
> >
> > I would appreciate a citation to answer my question. I believe
> > I was taught that Newton meant the same kind of mass that he
> > spoke of in his dynamics when he formulated his law of gravity.
> > The realization that there might be a problem came later, did
> > it not? It seems we should not be designating things that are
> > not Newtonian as Newtonian.
> >
> > Leigh