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Re: Questions on Neg. and Pos. Acceleration



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.