Re: free fall data repost

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

> True, with curve fitting or averaging of the acceleration values the old
> spark timer experiment can give good values. Do you mean that the
> acceleration values, calculated with simple successive differences as
> Ludwik wants to do, were ALL within 5 or 10%? I'd be very surprised, but
> my experience was only with the Behr freefall apparatus. Your equipment
> may have been better. Still, even if the old spark timer experiment gave
> good results, I'd never go back to it.

Our Behr freefall machine consistantly does as good or better than our 
picket fence hooked to computer.

> > we need to get back to
> > those PSSC type of equipment days when we used simple equipment and
> > _Made it Work_ and learned the frustration that accompanies all 'real'
> > physics inquiries.

> I couldn't disagree more. I think that this is a prescription for turning
> off yet another generation to physics, and for continuing teaching
> practices that appear to be inferior as judged by the literature.

Count me in, for the most part, with the Luddites.(with some reservation, I 
actually like both, methods)   Many computer based labs resemble black boxes 
and tend to obscure the physics that is going on.  More is being taught and 
demonstrated in the labs than some of that literature takes into account.

> These both showed that students doing kinematics experiments who had to do
> more traditional style analysis learned LESS than those who had real time
> computer graphing tools. The physics is in the interpretation and
> understanding of the graphs. Drawing graphs is important too, but it is a
> separate skill.

I must disagree here.  There is a lot of good physics in analyzing the 
free-fall spark tape witha meter stick and doing the successive differences 
by hand.  It really brings to life boring statements like delta X over delta 
T is the average velocity over an interval, in a hands on way (in the best 
tradition of hands on active style learning).  Lot's of physics is in areas 
other than interpreting and understanding the graphs!! The computer of 
course has to do this as well, but since it is all automated this fact tends 
to be totally obscured in the CBL's I've seen.  Just telling the students 
what the computer is doing doesn't cut the mustard as that is too passive of 
a learning situation in the laboratory.

Joel