Re: [Phys-l] g...

["John Clement" <clement@hal-pc.org>]

I looked at some of the books... that I have in my library to refresh my
memory.  The Real Time Physics curriculum does not seem to do anything with
g.  Flipping through McDermott tutorials did not enlighten with respect to
g, but they did use the conventional confusing notation for forces f for
frictional, N for normal...  Part of the problem with most curricula is that
they rely on a conventional book and the lecture may not be taught by a PER
trained professor.  Tougher in his book does sometimes use F for different
forces such as F_grav, F_normal, but then he illogically departs by using T
for tension as if it is a different type of force.  Knight adheres to
tradition, which I think is a grave mistake.  By not using a for all
accelerations, and F for all forces coherence has been decreased.

The idea of stressing interactions comes from Karplus, and is now appearing
in many texts, but unfortunately not before NTN2.  This is unpublished data
from a colleague in Finland who found that by doing interactions before the
other NTN laws greater understanding of NTN3 was achieved.  Similarly Laws,
Thornton & Sokoloff found that P should be introduced before E because it
improves understanding.  Knight ignores this research by having them in the
traditional order.  Workshop physics uses a_g and unfortunately calls it the
gravitational constant rather than the gravitational acceleration.  Again,
they use a conventional book along with the lectures.  As far as sequence
goes WP does seem to treat forces or possibly interactions before NTN2, but
again this is hard to determine because they have only published labs and
not an accompanying book.  I understand they have a modified book which is
designed to be a companion, but I have not seen it.

So perhaps the groups have not gotten together enough to make blanket
statements.  The U.Mass group is one of the few that has published and
integrated curriculum book which is coherent, and probably the only one to
also have a good teacher's manual which explicitly gives the rationale for
how and why the activities work.  I have found that most everything they
have done is very accurate.

John M. Clement
Houston, TX

> -----Original Message-----
> From: phys-l-bounces@carnot.physics.buffalo.edu [mailto:phys-l-
> bounces@carnot.physics.buffalo.edu] On Behalf Of Paul Lulai
> Sent: Sunday, November 19, 2006 11:59 AM
> To: Forum for Physics Educators
> Subject: Re: [Phys-l] g...
>
> I have somewhat limited knowledge of PER.  What PER sources recommend this
> sequence (perhaps in addition to the U.Mass Amherst group)?
>
> To double check:  the recommended sequence is 1-d w/o free fall, forces,
> a_g as a measure of gravitational field strength, 2-d?
>
>
> Paul Lulai
> Physics Teacher & Online Learning Coordinator
> St. Anthony Village Senior High
> Saint Anthony Village, MN
> 55418
> (w) 612-706-1144
> (fax) 612-706-1020
> plulai@stanthony.k12.mn.us