Re: trivial pedagogy

["Miguel A. Santos" <msantos@ETSE.URV.ES>]

> when it is moving to the left. Why do they often say "plus to
> the right and minus to the left" (which is wrong)?
>
> Ludwik Kowalski
 1.- Because in most of the cases, one draws the positive
x axis to the right, and
 2.- One can achieve a step forward (to the right) just by
'adding' a positive quantity to the current position.

 Why don't you relate this shift to a galilean transformation:
If one has a second reference fram displaced adistance a>0
to right, how does the position change? Ans: by substracting a.

 Would this help?

 Regards,
        Miguel A. Santos
        msantos@etse.urv.es