Drook's summary [on imprecise explanations] is, IME among the best definitions of where 'useful simplicity' finally runs into simplistic,
thus next confusing for someone who really does want to learn (a topic.)
Your nit-picking, especially where [M] is part of an (any!) equation, could not be more appropriate: if the sucker wants to wave-[M]-away: an imprecation on the lines of..
If you want us to ignore mass, write your equation wherein it CANCELS-OUT, so that our grey-cells are not driven to seppuku via, does-not-compute!
is demanded. Innit?
(Mentioned before: my quip on a physics test re "Bohr's somewhat nebulous Cloud Theory of the electron.." (in context of a slightly-fuzzy exposition of The Question.)
The humorless note later: Is this a pun? demonstrates yet another irritation of the then; Teaching of ScienceÂ; even in big, $-rich Institutes:
the undergrads are oft (then: always) fed to impoverished Grad Student TAs whose minds are in the aforementioned Clouds, quite far from the guaranteed confusions of
[in Physics especially! Newton Poundals anyone?] --too fucking-many! different Standard Notation schemas, intermixed by lecturers willy-nilly.
as-if: all of us were raised with English as a second-language to physics taxonomy.
Ah well, pedagogy is perhaps the least-comprehended topic of All Time, but big Institutions seem to spend very-few-$$$ focussing directly on that Black Hole.
(As you know, the first Feynman Lectures utterly snowed the Frosh/Sophs ... and some Seniors. And He was Mr. Clarity! We Are Doomed.)
..Seeks seppuku via Owsley-acid + some methyl-benzoyl-ecgonine + diacetyl-morphine:
(the Scientific 7% Solution?)