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Hmmmm....
I have not been following this thread.
Using the initial question statement provided by John C below, it
appears that
there is a force acting perpendicular to the line P-Q which passes
through position P.
However, we are asked to consider the effect of a force acting
perpendicular to
line P-Q, which passes through point Q, on a puck moving along the line
joining P-Q.
Somewhat over-specified??
Thought you'd want to know this
:-)
Brian W
John Clement wrote:
I for one, after reading the initial question statement do not thinkthere
is any ambiguity for this question. Compared to most questions I haveseen,
especially high stakes state exams, the question is posed quitecarefully.
If you look at only the part labeled #9, it is ambiguous, but not whenyou
read the initial lead in paragraph.Students
Reading ability is not completely a separate item from physics.
have to understand verbal descriptions of physics concepts as well asparagraph.
graphical, pictorial, and finally algebraic. Here is the lead in
------------------------11).
Use the statement and figure below to answer the next four questions (8-
The figure depicts a hockey puck sliding with constant speed v_o in aon
straight line from point P to point Q on a frictionless horizontal
surface. Forces exerted by the air are negligible. You are looking down
the puck. When the puck reaches point Q, it receives a swift horizontalkick
in the direction of the heavy print arrow. Had the puck been at rest ata
point P, then the kick would have set the puck in horizontal motion with
speed v_k in the direction of the kick.right,
------------------------
There is a diagram showing the puck initially going straight to the
and the kick perpendicular to the initial motion.the
I do not believe there is any way to reword this to make it clearer. Of
course there are students, seniors no less in HS, who do not understand
word negligible, so if they ask I tell them it can be ignored. Thereare
actually no "physics" terms such as force, velocity, or acceleration inthe
statement. Other than negligible it is in fairly plain language.It
There is the fact that many students will not go back to the problem
statement, and look only at the question. This is actually a cognitive
deficit, and could probably be categorized by the Feuerstein taxonomy.
may come under the lack of need for accuracy and precision or possiblyalso
excessive impulsivity. They may fail to look up V_k, mentioned in #9,but
defined in the initial paragraph.working
There is also the possibility that a student may have a very small
memory. But now we know this can be fixed or improved. There is aprogram
of computer driven exercises that permanently expands the workingmemory.
But it may be 20 years before schools actually routinely test for thisimpossible
deficit, and attempt to fix it. A small working memory makes it
to keep all of the factors in mind when answering. This would generallyof
show up on the Lawson 2 variable reasoning questions.
All of these cognitive factors serve as a severe barrier to learning any
science or math, but there are programs that can help fix them, and some
these have been around since 1980, so why aren't they being usedroutinely?
But of course it sometimes took a full generation for simple things likethen
sterilization to be routinely used in medicine.
John M. Clement
Houston, TX
It is ambiguity that started and sustained this thread. If there can be
multiple interpretations by professionals in the field, the question
ratherbecomes not whether the student uderstood the desired concept but
Clementwhether the student read the questioners mind. What is being tested -
physics or reading ability?
Bob at PC
________________________________
From: phys-l-bounces@carnot.physics.buffalo.edu on behalf of John
theSent: Sun 2/15/2009 12:25 AM
To: 'Forum for Physics Educators'
Subject: Re: [Phys-l] FCI answer?
In the statement for problems 8-11 it clearly states that V_k is the
velocity the puck would have starting from rest, and it clearly shows
missedforce in only one direction perpendicular to the initial motion. I
isthe problem statement because in the copy in Mazur's book it is on the
previous page. Mea culpa, that was my mistake. The problem statement
whenexact and clear. Then only 1 trajectory is correct in problem 8, and
you pick that, the answer to problem 9 is also clear. There is no
ambiguity.
_______________________________________________
Forum for Physics Educators
Phys-l@carnot.physics.buffalo.edu
https://carnot.physics.buffalo.edu/mailman/listinfo/phys-l
_______________________________________________
Forum for Physics Educators
Phys-l@carnot.physics.buffalo.edu
https://carnot.physics.buffalo.edu/mailman/listinfo/phys-l