Re: kinematics, traditional or not

[Hugh Haskell <hhaskell@MINDSPRING.COM>]

At 18:30 -0400 8/26/02, Bob LaMontagne wrote:
> I find this puzzling and very much outside my experience with students.
> Acceleration is a very concrete entity that students can visualize and have a
> feeling that they are "getting Physics" early on in the course.

That is certainly contrary to my experience. I think students have a
great deal of trouble visualizing acceleration, and I think that the
research shows that as well. McDermott showed a long time ago, that
beginning students do not pick up the concept acceleration quickly.
Early on, students frequently confuse velocity and acceleration, and
some even get the idea that all accelerations are 10 m/s^2--obviously
a fall-out from our habit of calling g an acceleration.

We have had some success by holding off on the concept of
acceleration until after Newton's laws have been introduced (which
happens after momentum has been studied). Once the students see that
NSL is going to involve changing velocity, they seem to be
intellectually ready to grasp the idea of acceleration, and they
learn about it in general before we introduce the special case of
constant acceleration and the kinematics equations--and the reminder
that these equations only apply to constant acceleration, is repeated
often. The also see lots of examples of non-constant acceleration, so
their first exposure to the idea is not that of constant
acceleration, and they don't get into *physics* (that is, the part
they learn after doing kinematics in the traditional sequence)
thinking that acceleration is some magic constant that they don't
have to understand, only know how to plug into equations.

Students can learn a lot of physics without having to burden
themselves with the abstract concept of acceleration. Then when the
idea has been properly motivated, they will do a lot better at
learning it.

Hugh
--

Hugh Haskell
<mailto:haskell@ncssm.edu>
<mailto:hhaskell@mindspring.com>

(919) 467-7610

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