Re: [Phys-l] pseudo-force

[Ludwik Kowalski <kowalskil@mail.montclair.edu>]

I think that a centrifugal force F is real; it can be measured. Suppose 
a ring is sliding along a rotating stick. We expect F=m*a, where a is 
the ring acceleration, with respect to the stick, directed  away from 
the center. One can measure static F (with a calibrated spring mounted 
on the stick) and one can measure the acceleration (when the ring is 
allowed to slide). What is wrong with this point of view?

Ludwik Kowalski
Let the perfect not be the enemy of the good.

On Oct 26, 2006, at 7:23 AM, Anthony Lapinski wrote:

> Pseudo forces are usually mentioned during circular motion. Everyone 
> knows
> that when you turn your car sharply to the right, you move to the 
> left. So
> you naturally think there is an outward "centrifugal" force on you. But
> it's really just your inertia -- your tendency to want to move in a
> straight line. There isn't an outward force (on you) because every 
> force
> must have a source! So we call these outward forces "pseudo forces." 
> There
> IS an outward force, but it does not act on the object in question  
> .It's
> just the reaction force of the net inward (centripetal) force for an
> object moving in a circle. Or spin a stopper. The inward (net) force is
> the string on the stopper. The reaction force is the stopper on the
> string. It is outward, but does NOT act on the stopper (as many people
> believe).
>
> This is a very difficult concept for my students, and for most people.
>
> Hope this helps!
>
> Forum for Physics Educators <phys-l@carnot.physics.buffalo.edu> writes:
> > Some questions:
> >
> >  What do people mean by the term "pseudo-force"?
> >
> >  Is a pseudo-force a force?
> >
> >  Why is it called a pseudo-force?
> >
> >  Is this concept crucial/useful/marginal/unhelpful?