Re: Questions on Neg. and Pos. Acceleration

[Joel Rauber <Joel_Rauber@SDSTATE.EDU>]

I don't know the name of the below poster (they didn't sign their posting),
but wanted to mention that I'm trying this approach for the first time this
semester in my calculus based introductory course.  Having done it for the
first time last spring in the 1st semester algebra based course, which I
taught for the first time in my life.  I did it because the textbook we use
in that course approaches it that way (kinda, sortof), 1d kinematics using
vectors.  I haven't tweaked how I do this completely but I think it has been
helpful.  The textbook is one by Wilson and Buffa.  I think it is a good
idea and look forward to seeing your description in TPT, assuming they
accept it.

Joel Rauber

>  The issue of "positive and negative acceleration" would be
> clarified for
> students if a vector approach were adopted for kinematics,  including
> one-dimensional kinematics. The standard approach which
> introduces vector
> quantities after one dimensional kinematics is an inconsistent one, as
> displacement, velocity, and acceleration are no less vector
> quantities in
> one-dimension than they are in two and three dimensions. By
> adopting this
> approach, one discusses the components of velocity and acceleration
>  properly subscripting the quantities) in one-dimensional
> motion, which may
> be positive or negative as they can be for all vector quantities. This
> reduces the opportunity for confusion regarding the magnitude
> of a vector
> quantity (always positive and with no subscript) and the components
> (positive or negative and with subscripts). I have
> successfully used this
> approach for many years both for translational motion and for
> rotational
> motion about a fixed axis. I have submitted a note to The
> Physics Teacher
> which includes more detail.