In his PhysLnrR post of 3 Dec 2007 titled "Student difficulties with
Normal Force?" David Brookes wrote [bracketed by lines "BBBBB. . .
."]:
BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB
Does anyone know of a published study that documents advanced . .
.[what is meant by "advanced"?]. . . . student difficulties with the
"normal force" concept. For example, with the inverted rollercoaster
doing the loop, we all know that, at the top of the loop, some
students will draw the normal force on the coaster car pointing
vertically upwards and set it equal to mg. Other than a brief
mention of such difficulties (block on a slope) in Kim & Pak (2002,
AJP), I'm drawing a blank on this one. Your help would be greatly
appreciated.
BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB
Aside from Kim & Pak (2002), I'm not aware of any published studies
that explicitly document student difficulties with the "normal force"
concept, but such difficulties are well known to most physics
instructors.
In my opinion, student difficulties with forces named normal, weight,
tension, centripetal, centifugal, friction, tension, reaction, etc.
would be much alleviated if students in beginning mechanics courses
were brought to realize that in the Newtonian world:
a. ALL forces are due to interactions between two bodies A and B;
b. Interactions are either "action at a distance" (usually in a
beginning mechanics course only gravitational), or "touching" between
bodies which touch one another (the usual term "contact" is often
less meaningful to beginning students).
c. Forces should *always* be labeled F(on A by B);
d. Newton's Third Law may be written:
vector F (on A by B) = - vector F (on B by A).
So the Newton's Third Law reaction to any force vector F (on A by B)
can always be obtain by the "AB switch" as - vector F (on B by A).
REFERENCES
Hake, R.R. 1992. "Socratic pedagogy in the introductory physics lab,"
Phys. Teach. 30: 546-552; updated version (4/27/98) at
<http://www.physics.indiana.edu/~sdi/SocPed1.pdf> (88 kB). See also
Hake (2002).
Hake, R.R. 2002d. "Socratic Dialogue Inducing Laboratory Workshop,"
Proceedings of the UNESCO-ASPEN Workshop on Active Learning in
Physics, Univ. of Peradeniya, Sri Lanka, 2-4 Dec. 2002; online at
<http://www.physics.indiana.edu/~hake/Hake-SriLanka-SDIb.pdf> (44 kB).
[UNESCO = United Nations Educational, Scientific, and Cultural
Organization; ASPEN = ASian Physics Education Network.]
Hake, R.R. 2008. "Design-Based Research in Physics Education
Research: A Review," in A.E. Kelly, R.A. Lesh, & J.Y. Baek, eds. (in
press), "Handbook of Innovative Design Research in Science,
Technology, Engineering, & Mathematics (STEM) Education." Taylor and
Francis, online at
<http://www.physics.indiana.edu/~hake/DBR-Physics3.pdf> (1.1 MB).