Date: Tue Mar 10 16:00:36 2009 Back to Contents ------------------------------------------------------------------------

Author: Bill Norwood

Subject: Re: Free Fall With PASCO Photogates


Hi David,

I really appreciate that you have invested thought, time and effort in
informing me and explaining this experiment.

No, we couldn't get rid of the Behr apparatus immediately, at least because
that would necessitate a whole new lab manual write-up, and those "come

It just could be, however, that we could use our digital photography, which
is now well worked-out for the air table...

Best, Bill

-----Original Message-----
From: [] On
Behalf Of David Sturm
Sent: Thursday, February 26, 2009 11:33 AM
Subject: Re: [tap-l] Free Fall With PASCO Photogates

Bill: The Behr-type Free Fall is a classic. Do I read you correctly in
that you are wanting to be rid of them?

Classically in the laboratories where I've used them (Auburn, Wake Forest)
we only had one in the lab room. The TA made the spark-tape in real time
with the student. If it's connected with a control switch, there's not much
chance of shocking a
student: the only time your hand is near is to lift the dropper back up into
the electromagnet. At least, unless someone purposely intends to create a
shocking situation!

As I recall, the point of the spark tape is to use the dots to create a
differential calculus method, taking the change in x to get a v, and taking
the change in v to get a (g, that is.)

The PASCO free fall apparatus is of a different nature. If you have the
DROP plate assembly that plugs into the photogate base. That just gives a
fall time, and doesn't do the differential method that you get from spark

What you seem to have are the necessary photogates for doing Velocity and
Acceleration on an Air Track.

If you just want to find g, drop a Picket Fence through the "#2" auxiliary
photogate connected into a Science Workshop box, or the Digital to USB
Pasport sensor set.

Those base photogates though are perfect for Conservation Momentum
experiments on the Air Track.


David E G Sturm - - 1.207.581.1241
--Physics & Astronomy Instructional Laboratories
--Bennett Hall Lecture Demonstration Facilities
--Mainely Physics Road Show --PIRA President '08-09
Dept of Physics & Astronomy -- University of Maine
5709 Bennett Hall -- Orono ME 04469-5709

From Tue Mar 10 16:00:36 2009