Re: [Phys-l] Movie Physics Gafs

[chuck britton <cvbritton@mac.com>]

Back in the days of giving summer workshops for 
teachers I bought a supply of brass pins (for 
NON-magnetic items) and el cheapo compasses from 
Oriental Trading for general magnetic stuff.

The 'brass' pins turned out to be brass plated 
steel and the compasses all had aluminum needles 
! ! !

I had the joy of 'correcting' the polarity of our 
Sargent Welch re-magnetizer box as well.

(When was it that the physics books stopped 
labeling the N end of a compass as the 'North 
SEEKING' pole!!!!)  grrr. I remember Dull Metcalf 
and Williams doing this back in the bad-old-days)

I started hanging a bar magnet from the light 
fixture and asking students (and fellow teachers) 
which end would point towards Santa Claus. (or 
Canada - for the non-believers)
.
At 1:43 PM -0500 9/12/11, John Clement wrote:
> This misconception is well documented by PER 
> researchers, so one should not be surprised. 
> The Minds on Physics series very sensibly covers 
> all of the long range non contact forces in one 
> section.  So students are exposed to 
> electrostatic, magnetic, and the general 
> gravitational law all at once.  The distinction 
> between how the forces are produces is clearly 
> exposed.  So in testing for understanding 
> questions are asked that reveal whether the 
> confusion between electrical, magnetic, and 
> gravitational forces is present.  There is one 
> school educational website that talks about 
> magnetic interactions as if it were electrical 
> in nature and uses terms which I consider are 
> designed to promote this misconception.
>
> If you want to find out what students think just 
> ask "What can magnets pick up?" and they will 
> almost invariably say "metals".  MOP has them 
> actually test a variety of materials such as 
> aluminum, steel, copper, their own jewelry... 
> This has not been done in the lower grades, so 
> they are severely misconcepted about how magnets 
> work.
>
> But when this sort of thing is put into 
> commercial movies, you know that the directors 
> don't know simple physics either.
>
> John M. Clement
> Houston, TX
>
> >  Here is a video showing a compass made from a needle
> >  magnetized with a silk cloth!
> >
> >  http://www.youtube.com/watch?v=wIGbNJDYdnM&feature=player_detailpage
> >
> >
> >  From: Bob Sciamanda
> >  Sent: Monday, September 12, 2011 10:00 AM
> >  To: Forum for Physics Educators
> >  Subject: [Phys-l] Movie Physics Gafs
> >  I just watched ⤦The Edgeâ¤ù (1997, Anthony Hopkins, Alec Baldwin).
> >  Lost in the wild, Hopkins (playing a very knowledgeable
> >  outdoorsman) makes a compass by floating a needle on a leaf.
> >
> >  But he ⤦magnetizesâ¤ù the needle by rubbing it with a piece of silk!
>
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