**Is mass the least complicated "Conservation Principle?**
Below I update my ideas. I am not trying to "bump" the topic.
What Newton (and others) meant is less important than what's needed today for ourselves, our students. For applications today, might some reformulation be of value.
********************
Newton's Laws and the "conservation" ideas germinated in relativlely the same time period. The
seminal "conservation" idea addressed energy of a Body. So there was supposed "Conservation of Energy."
Thence, logically might momentum of a Body be conserved? And in afterthought "Conservation of Mass" makes sense for the Body - implicitly.
The matter of interest was modelled as a Body (mass at a point and having no extent). "Conservation of mass" applied to "some specific mass, selected at a time <b>t*</b> thereafter modeled as a point with no extent nor "boundary." The Body exists in space we call "extrinsic space." Other (more logical) models of matter exist in "extrinsic space" in terms of their centers of mass, but als in "intrinsic space" meaning the mass might have shape, deform and so.
The idea "mass of a Body is conserved" is represented by the mathematical equation:
(a) m(Body) = const. which is a non-homogeneous equation. A better statement is:
(b) d[m(Body)]/dt =0. A question here. Why is **(b)**superior to **(a)**?
=====================
Comments Here:
1) This is "about in Newton's time." "Body" is the model.
2) As we see it, the idea, "Conservation of mass" has mathematical representation as an equation with
a property of the Body as dependent variable.
3) The equation "conservation of mass" is a "property equation" for the Body.
I am not trying to "bump" my topic. Rather to develop it. Thank you
*
Last edited by THERMO Spoken Here; Sep 22nd 2018 at 01:54 PM.
Reason: correction needed
* |