Re: Cause and Effect

[Rick Tarara <rtarara@SAINTMARYS.EDU>]

----- Original Message -----
From: "Leigh Palmer" <palmer@SFU.CA>
> > I believe the FCI has several problems that bring to light this
> > misconception (that a projectile accelerates in the air in part due to
the
> > force used to send it).  Am I mistaken?
>
> I recall that misconception. Would that not still be cause preceding
> effect?

The misconception does seem to be a cause/effect one.  The students,
thinking more like Aristotle than Newton, see a motion and 'know' that
_motions_ are caused by forces.  If I throw a ball straight up, the upward
motion (to them) must be due to an upwards force.  Many will attribute this
force to the hand.

The problem here is the difference between contact forces and
action-at-a-distance forces and of course having Aristelian ideas about
motion rather than Newtonian.  The fact that the motion induced by the force
of the hand continues beyond the hand but the force of the hand ceases once
the ball leaves the hand, is a major stumbling block for many students.  The
FCI will illuminate this misconception well and it will show up for many
AFTER completing their study of Newton's Laws.

Rick

**********************************************
Richard W. Tarara
Associate Professor of Physics
Saint Mary's College
Notre Dame, IN 46556
rtarara@saintmarys.edu

FREE PHYSICS INSTRUCTIONAL SOFTWARE
www.saintmarys.edu/~rtarara/
PC and MAC software
NEW! E&M package for the  Animated Chalkboard
CD-ROMs now available
******************************************************