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



Bob LaMontagne wrote:
I have a conceptual problem with this. I can conceive of a situation where
there are many identifiable forces (tension, gravity, wind resistance)
acting on an object, but a point mass has only one acceleration - the second
derivative of its position - and it has only one position. There are
certainly accelerations it might have had if each of the forces acted
individually - but they don't.

I think it's simply bad pedagogy to set up a net acceleration that is
defined as a sum of a collection of phantom accelerations

There's nothing phantom about it. The car accelerates relative to
the table, and the table accelerates relative to the floor. The
acceleration vectors add.

I think it is simply bad pedagogy to suggest that the vector-addition
law applies to some vectors and not others. I think it is simply bad
pedagogy to suggest that the substitution property of equality applies
to some quantities and not others.

Mathematical axioms and bedrock principles are not to be trifled with.