Re: [Phys-l] ? passive force of constraint

[Scott Goelzer <s.goelzer@comcast.net>]

If you start to dig, many students call passive forces _pressures_  
and active forces (what they or what they can imagine themselves  
actively doing) forces.

Scott



On Jul 18, 2007, at 9:50 PM, Dan Crowe wrote:

> I think that John is asking about passive, as opposed to active,  
> forces,
> where an active force is a force exerted by an animate organism and a
> passive force is a force exerted by an inanimate object.  Not all
> passive forces are forces of constraint.  Gravitational and  
> macroscopic
> electrostatic forces are passive forces.
>
> Many students in introductory physics courses believe that only active
> forces exist.  The following is a typical statement: "The table  
> doesn't
> exert a force on the falling ball: It simply gets in the way."   
> Physics
> education research has shown that addressing this preconception helps
> many of these students to better understand normal force, tension and
> other passive forces.
>
> Daniel Crowe
> Loudoun Academy of Science
> dan.crowe@loudoun.k12.va.us
> > > > jsd@av8n.com 07/18/07 7:47 PM >>>
> Hi --
>
> A couple of times recently I've seen the term "passive force".
> I've never been entirely sure what that meant.  I reckon it
> is something akin to a force of constraint.
>
> Questions:
>
> 1) If there are really two ideas here, rather than one idea
>  going by two different names, what are the ideas?  What
>  is the distinction between the two ideas?
>
> 2) If there is just one idea here, is there any reason to
>  prefer one terminology over the other?  Based on what
>  little I know at the moment, I would tend to favor
>  "force of constraint" on the grounds that it is more
>  descriptive and more conventional ... unless somebody
>  has a good counterargument.
> _______________________________________________
> Forum for Physics Educators
> Phys-l@carnot.physics.buffalo.edu
> https://carnot.physics.buffalo.edu/mailman/listinfo/phys-l