Re: inertial forces (definition)

[Leigh Palmer <palmer@SFU.CA>]

> 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