Re: CAUSALITY IN PHYSICS (was drag force)

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

Leigh Palmer wrote:

> Given the relation F = ma, one must recognize that the relation
> applies to a physical model in which a particle undergoes
> acceleration simultaneously with the application of a force.
>
> Question: is force the causal agent to which the effect of
> acceleration can be attributed?
>
> Answer: we have not enough information to make that determination.

In my presentations F is a CAUSE of acceleration. Mass is the
same no matter how large the force (classically). A given force
acting on a different m produces a different a. Simultaneity and
rigidity are implied. Is this wrong in the first physics course? If
so then why? Likewise a dop, for example from a battery, is a
CAUSE  of current. That is a common approach, I suppose.
Ludwik Kowalski




> .
>
> Hold on - isn't this a simple case? Yes, it is. It is *too* simple. By
> hypothesis this equation applies strictly to a model. The model closely
> resembles the phenomenon of a a physical body moving under the influence
> of an applied force. It is in the details which distinguish the model
> from the physical system that the causal relation between force and
> acceleration is to be found. The gradual buildup of the force over a very
> short time after its initial application and the slight compression of
> the body over this same time interval will corroborate the causal
> relation we naturally assign. In light of what is really happening the
> metaphysical questions are readily seen to be trivial.
>
> The philosophical statement is about models; causality may not apply to
> models which are insufficiently physical. The very word "simultaneously"
> should set off alarm bells in the mind of any modern physicist.
>
> Leigh