Re: [Phys-l] pseudo-force

[John Mallinckrodt <ajm@csupomona.edu>]

Ron McDermott wrote:

> I suppose it would be pointless to attempt to point out that one  
> DOESN'T "feel" a centrifugal force, but certainly does feel a  
> centripetal force?

In principle, I also like to talk about "feelability" because it  
emphasizes the identical nature of gravitational and centrifugal  
forces as "unfeelable" inertial (or fictitious, or pseudo, or frame)  
forces and distinguishes them from "interaction forces," especially  
of the contact variety.  On the other hand, I really dislike talking  
about "centripetal force" because it sounds like a force that only  
acts on objects moving along circular paths and that does so BECAUSE  
they are moving along circular paths.

The so-called "centripetal force" is nothing more than the  
instantaneous component of the NET force on an object transverse to  
its trajectory and it points (by definition) toward the instantaneous  
center of curvature of the trajectory.  When observing an object  
moving along a circular path in a rotating frame, the centrifugal  
force may even contribute to the so-called "centripetal force"!

John Mallinckrodt

Professor of Physics, Cal Poly Pomona
<http://www.csupomona.edu/~ajm>

and

Lead Guitarist, Out-Laws of Physics
<http://outlawsofphysics.com>