Re: elastic collisions

[John Clement <clement@HAL-PC.ORG>]

> In the 5th edition of Physics, by Resnick, Halliday and Krane,
> major changes are made from the previous editions.  One of the
> most significant is the moving of all discussion of energy to the
> end of the mechanics section, where it is used as a unifying
> theme.  This is, I know, in vogue among physics teachers these
> days, and, while I'm not excited by it, I'm not unhappy about it either.
>
> Discussing momentum and collisions before energy does raise a
> question, though.


I think it is appropriate to comment on why this is currently in vogue.  It
is due to research by Laws, Thornton, and Sokolff, and not just a fashion.
They found that just rearranging the curriculum pushes up scores on the
FCI/FMCE.  I do not know which of their papers mentions this, as I learned
about it in one of their workshops when Priscilla mentioned it.  Another
thing that they found is that all 1-d cases should be explored before higher
dimensional cases.  I can not give the exact magnitude of the increase, but
I gather it is a robust result.  This has been dubbed "the new mechanics
sequence".  Whether there are other sequences which will produce equivalent
gain is to my knowledge unknown.

However I suspect that this new sequence will not produce enough increased
gain to be perceptible in a conventional physics course.  The higher gain
will probably only be noticed in an "interactive engagement" course.

John M. Clement
Houston, TX

This posting is the position of the writer, not that of SUNY-BSC, NAU or the AAPT.