Re: [Phys-L] kinematics objectives

[John Denker <jsd@av8n.com>]

On 05/08/2013 07:36 AM, Philip Keller wrote:
> ..... here' s my summary so far, in no particular order.  Each of
> these 8 paragraphs will be paired with a simulation.
>
> I welcome any comments or suggestions.

Two points:
  1) If the summary is meant to serve as notes to yourself, summarizing
   what you plan to cover, it's just fine.

   Similarly, if the summary is meant to tell folks on this list what
   you plan to cover, it's just fine.

  2) OTOH if the summary is meant to be passed out to students early in
   the course, telling them what you plan to cover, it's not ready to go.
   The summary uses a lot of physics lingo.  It uses the terminology
   carefully and correctly ... but that doesn't do the students any good,
   because they don't (initially) know the terms, and more importantly 
   they don't even understand the concepts to which the terms refer.

   2a) As an ultra-simple example, if a student doesn't grasp the concept
   of weight as distinct from mass, saying it louder ("WEIGHT" versus
   "MASS") doesn't help.

   2b) There's no point in talking about a "force perpendicular to the
   velocity" if the student doesn't have a clear notion of what perpendicular
   means, much less what force and velocity mean.

   2c) As a somewhat deeper example, consider using a string to pull a
   block across a table.  All experience (and an ocean of literature)
   tells us that in many cases, if you talk about "the force" on the 
   block, a naïve student will interpret "the force" to be the tension
   in the string, i.e. the /intentional/ force.  They don't count 
   friction as a force.  They aren't intentionally neglecting it; they
   just don't think about it at all.  Friction is considered so "natural"
   that it requires no explanation.

   Galileo revolutionized physics when he changed the point of view.
   He decided that the frictionless state was the "natural" state,
   requiring no explanation ... and that friction had to be accounted
   for as a force, on the same footing as tension in the string.

Remark: Giving the students an outline early in the course has its
disadvantages as well as advantages.  The #1 risk is that showing 
the students a long list of things they don't understand might
intimidate and discourage some of them.

Suggestion:  Any initial outline should be just an outline.  That is, 
it should not attempt to go into details about concepts the students 
don't yet understand.  Perhaps something like this rough draft:

 *) We will learn a lot of new concepts.  At this point you are not 
 expected to have any great understanding of the following points, 
 but this outline may serve as a roadmap of where we are going:
  ++ the great symmetries and conservation laws
    -- conservation of energy
    -- conservation of momentum
    -- conservation of charge
    -- Galileo's principle of relativity
    -- et cetera
  ++ the concept of mass as distinct from weight
  ++ the concept of ideal motion, free of all forces
  ++ the concept of accounting for /all/ forces
  ++ the concept of point particle (as opposed to extended object)
  ++ a framework for precisely describing particle motion, including 
   time, position, velocity, and acceleration
  ++ scalars and vectors
    -- vector velocity (in contrast to scalar speed)
    -- vector acceleration (in contrast to scalar acceleration)
  ++ the laws of motion
    -- simplified applications thereof
    -- real-world applications thereof
  ++ the bond between theory and experiment
  ++ advanced techniques for learning, memory, and reasoning


> I am still an FCI skeptic on many levels

Me too!  I changed the Subject: line because this is an important topic,
and I couldn't bear to look at it through FCI-colored glasses.