Re: free fall data

["Lawrence L'Hote" <llhote@mail.coin.missouri.edu>]

> As you discovered with your spreadsheet experiment, it takes an
> exceedingly high level of precision in the position measurements to obtain
> a horizontal acceleration vs. time graph. The old spark timer lab that
> many of us used to teach had terrible acceleration graphs too. 

I built a spark free-fall apparatus nearly 30 years ago.  I use it with
a large induction coil and a half-wave rectifier.  The apparatus looks
like a Rube Goldberg throwaway...but IT WORKS.  I use 60Hz as the time
base and the ball falls about 1 meter I am able to consistently able to
get 'g' with less than 10% error.  It is not unusual to get the whole
class(7 work groups) to get g with less than 5 percent error.  I have
sets of the CBL equipment but use it infrequently because I firmly
believe the students learn very little from the gimcrackery of a black
box electronic device that leaves the student with the impression that
good physics can only be done with magic boxes...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. 
.....now off my soap box and back to those nagging, unscored papers.

<<<Larry>>>