Re: inertial forces (definition)

[Bob Sciamanda <trebor@VELOCITY.NET>]

Excellent point, Brian
Isaac says:
" The power of gravity is of a different nature from the power of
magnetism;  for the magnetic attraction is not as the matter attracted.
Some bodies are attracted more by the magnet; others less; most bodies not
at all. . .
and in receding from the magnet decreases not in the duplicate but almost
in the triplicate proportion of the distance . . ."

I think he is saying that gravity is a universal property of stuff and
should be describable in terms of "quantity of matter" alone; magnetism
is something else . . .(???)

Bob

Bob Sciamanda (W3NLV)
Physics, Edinboro Univ of PA (em)
trebor@velocity.net
http://www.velocity.net/~trebor

----- Original Message -----
From: brian whatcott <inet@INTELLISYS.NET>
To: <PHYS-L@lists.nau.edu>
Sent: Tuesday, October 19, 1999 9:11 PM
Subject: Re: inertial forces (definition)


> At 20:18 10/19/99 -0400, Bob Sciamanda wrote:
> > Proposition VII, Theorem VII of Isaac's Principia is entitled:
> > "That there is a power of gravity tending to all bodies, proportional
to
> > the several quantities of matter which they contain"
> >
> > He thus perceived both the "force of inactivity" (below) and the force
of
> > gravitation to be each proportional to the same property of an object:
the
> > "quantity of matter".  I don't think he saw anything striking in this;
he
> > knew of no other force laws with which to see a contrast....
>
> > Bob Sciamanda
>
> I am not quite sure of the sense in which Newton may be said to be
> unaware of other force laws: in the lines immediately preceding
> those you quote above, Newton remarks,
> " The power of gravity is of a different nature from the power of
>  magnetism; for the magnetic attraction is not
> as the matter attracted..." [i.e proportional to mass]
>
> Elswhere he mentions an inverse square law of magnetism
> (though here he suggests it may diminish as much as by an
> inverse cube of distance "by rude observations")
>
> brian whatcott <inet@intellisys.net>
> Altus OK