Re: apparent weight

["Rauber, Joel Phys" <RAUBERJ@mg.sdstate.edu>]

> I am not saying that noninertial frames should be used to solve physics
> problems. These frames should be avoided, especially in three-dimensional
> situations (playing with a ball on a rotating platform).

Why should they be avoided; one should use the frame that makes the 
calculation the simplest.  In some cases they should be avoided, in some 
preferred.  I believe it was mentioned in a previous incarnation of this 
subject that people who do hydrodynamic calculations in weather prediction 
use the non-inertial frame of the earth's surface, I gather, because its 
simpler for them to do it that way.


> I know, you will say "why teach them something they must unlearn in more
> advanced physics courses?". And you know what my answer would be, "most of
> these students ...". In my opinion, no harm can result from explaining
> certain things in terms of *centrifugal* forces, magnetic *poles*, light
> *rays*, etc. Yes, I am sticking out my neck again. Later courses, if any,
> may elaborate on limited utility of simple explanations and deal with
> hidden nuances. What is wrong with this attitude. Explain why you think
> this attitude must be rejected.

I would argue that they don't have to "unlearn" anything in the advanced 
course, when they have learned *centrifugal*, magnetic  *poles* etc; what 
they have to learn is the differences that are caused by using inertial or 
non-inertial frames of reference and I would hope learn to be equally at 
home in either type of frame (something I haven't achieved yet).

Joel