What observers feel
> > It is the interpretation of the
observer that an outward force is acting
> > on him when he is in a rotating frame. What he actually feels
is the
> > pressure between him and sides of the car. Since he knows
that
> > he is not exerting any muscular effort to produce this pressure
and
> > since he cannot bring himself to believe that an inanimate
thing like
> > a car can exert such a pressure on him, he interprets that
some
> > mysterious force is pushing him towards the sides of the car.
This
> > he calls 'centrifugal force'.
>
> I wouldn't have said that.
>
> It is not traditional and not recommended to ask what the
observer
"feels".
> Observers are paid to observe the objects in their vicinity, not to
worry
> about what they themselves are feeling.
>
I _would_ discuss what the observer feels. The students have
experienced
the situation described above. They can relate to this and to
their
'feelings' while on various carnival rides. You can use that
experience to
then discuss the physics. If one is to analyze the non-inertial
frame both
as viewed from an inertial frame and as viewed from within the
accelerating
frame, then it seems to me that it is essential to analyze what the
observer
'feels' in order to bring understanding to the situation.
Rick
This discussion reminds me of an incident that occurred when I was
young. My father (not a scientist) and I were in some vehicle
(perhaps a train?) that was stationary until suddenly bumped from the
back. I said something about being thrown back (I wasn't a
physicist yet!) and my father thoughtfully pointed out that actually I
was now forward of where I'd originally been, I must have been pushed
forward instead. Since I remember that incident, I must have been
pondering it for a long time until I really understood what
occurred.
Laurent Hodges, Professor of Physics
12 Physics Hall, Iowa State University, Ames, IA
50011-3160
lhodges@iastate.edu
http://www.public.iastate.edu/~lhodges