Chronology | Current Month | Current Thread | Current Date |
[Year List] [Month List (current year)] | [Date Index] [Thread Index] | [Thread Prev] [Thread Next] | [Date Prev] [Date Next] |
[Original Message]to the
From: John Denker <jsd@av8n.com>
To: Forum for Physics Educators <phys-l@carnot.physics.buffalo.edu>
Date: 8/14/2006 1:44:26 PM
Subject: Re: [Phys-l] Collision of irregular bodies
Bob LaMontagne wrote:
In the usual "plane of contact" collision, the force is perpendicular
plane.
Really? How do you know? What's the measure for "usual"?
Has anybody done an experiment that shows the force is
reproducibly perpendicular to the plane of contact?
In every experiment I can think of, there are readily-observable
force components in the plane of contact. Previously mentioned
examples include
-- billiard balls(*)
-- dropping a broomstick onto the floor
Another example that comes immediately to mind is table tennis
(ping pong). I've seen 10-year-olds try to play the game using
only normal forces ... but I cannot consider that the "usual"
case. The first kid who figures out how to use the non-normal
forces will win every time.
Are these not valid observations? Are they not representative
of the "usual" case???