Re: Being careful with dimensions (was Re: i,j,k things)

[Joel Rauber <Joel_Rauber@SDSTATE.EDU>]

Gang,

> > My problem with this is that I don't like the expression
> "F=2i-3j" that
> has
> > been used as an example throughout this thread.  In fact I
> hate it.  I
> > would always write "F = (2N)i - (3N)j".
> >
> > Am I in the minority???

The way I write it is "F = (2i - 3j) N"
Which of course begs the question;  unless you interpret my style as meaning
the units go with the vector and the components or the unit vectors; (I
don't make such an interpretation, I have a more live-and-let-live
philosophy until I decide to get positively pedantic).  Any comments on the
above style of writing the vector?
> Moreover, I think texts set a HORRENDOUSLY bad example when they write
> things like, "The position of a ham sandwich is given by x =
> 3 - 5t + 2t^2,
> find its speed at t = 5 s."

I agree with John above, but am just as egregious as the texts, out of
laziness.  it gets awfully tedious to write:

x = 3m - 5 m/s t + 2 m/s^2 t^2

but I admit its laziness, and my students would probably be better served if
I did it more properly; of course, there is a price, fewer examples worked
in class.

> O.K., I know this probably qualifies as a pet peeve and that most pet
> peeves are at least borderline overreactions, but this one really does
> push my buttons.

True too, but not all borderline overreactions are really overreactions.

Joel Rauber