Re: F=ma

[Ludwik Kowalski <KowalskiL@MAIL.MONTCLAIR.EDU>]

Another reflection (speculation). Our brains, washed and
unwashed, are lazy. So by facing the unknown we try to
think in terms of

   Effect = cause * property of what is affected

I am not sure that the desire to understand the world in terms
of causal relations is brainwashing, Leigh. It may correspond
to the fact that things are more than "equivalent", John D, they
may be consequences of other things. Did humans invent the
cause and effect relation or did they discover it first and then
created words (such as: mass, time, why, because, force, work,
heat, energy, supply, demand, etc.) to communicate the idea?
Or perhaps the brain cells are already structured to look for
causes of what happens?

We love simplicity; lazy brains favor linear relations. So we
invent terms to make causal relations linear. When we discover
that I is not proportional to R=rho*L/A (the heating effect of
current) we make rho proportional to a change of temperature,
in the first approximation.

Once the terms are already invented we often have no choice
but to accept the fact, not all causal relations are linear. I am
glad to be a physics teacher, not a philosopher. But it is fun to
speculate. To understand is to find a satisfactory causal relation.
To teach is to promote understanding. To explain is to express
understanding. How would I define such pedagogical terms
without accepting the existence causal relations?
Ludwik Kowalski

Responding to Leight, I wrote:

> This 1/m (see below) is like conductivity=1/resistivity.
> To what extent is I=V/R a good analogy for a=F/m?
>
> Leigh Palmer wrote:
>
> > I've always looked at Newton's second law as being somehow incomplete.
> > It does not include what I consider to be a causal element. Forces do
> > cause accelerations, at least that is what my intuition tells me, or I
> > was successfully brainwashed a long time ago. (This latter possibility
> > is often referred to as "common sense".) Newton's law, especially
> > written with a "coefficient of inertia", the mass, does not imply that
> > forces cause acceleration. If one were to write it as a=HF, where
> > H=1/m is the coefficient of compliance (or some other such name) it
> > would look better to me. ...