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Re: [Phys-l] Equations (causal relationship)




On 01/05/2006, at 5:25 PM, John Denker wrote:

Brian McInnes wrote:

... Forces are external to a
particle, there can be many (or none) of them acting, Acceleration
is an attribute of a particle - as such, in a given reference frame,
it must have a single value.


That is your opinion, not a law of physics.

If you think there is any physical basis to that assertion, pleeease
describe an experiment such that the observable outcome can be correctly
predicted using that assertion, and not correctly predicted otherwise.


There were four assertions in my e-mail. Two related to forces, two others related to accelerations. Which one(s) cannot you accept?

(1) Forces are external to a particle.
I'd rather think of a force as an interaction between a particle and its environment but, in the context, of this discussion, we all seem to be looking at the particle (or the body).
There is a physical basis to this assertion,

(2) There can be many (or no) forces acting on the particle.
There is a physical basis to this assertion.

(3) Acceleration is an attribute of a particle.
Again, here is a physical basis to this assertion.

(4) In a given reference frame the acceleration of a particle has a single value.
And yet again, there is a physical basis to this assertion.

So, let me know which one or more of these 4 assertions you would like me to spell out.

Brian McInnes