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[Phys-L] Re: Energy & Projectile Lab


You are in luck if you have some counters. I inherited a bunch of home
made (UCB electronics shop) photo. gates. They require an ac supply to
power the small incandescents. The photocell is self powered, I think
(not a photo conductor). If you are interested I'll send you a pair.
You'll need to be or have a person someone adept at interfacing it w/ a
counter. An alternative is I also have a bunch of the old Vernier
ULI's; the software is now free, but requires the old RS232 (I think *)
connection, not USB. This could be a project for one of your gung ho
students. Since I'm retired AND if it works I'd like reimbursement for
the post (only). Actually the tacit? agreement w/ the dept. (Berkeley)
was I give them away. If you're interested, but a little doubtful I'll
send pics. of the stuff.

* Yes if used w/ IBM platform. Berkeley Physics used Macs or Apples?

Another alternative is I also have from NPS and Berkeley ancient clock
type timers. A nice project would be to interface a solid state relay
to switch on and off. Back in the 60's? they called mixed tube and
transistor stuff hybrid; this gives new meaning to the term.


p.s the photogates were made for a timer of which I only have a few,
sorry. With one of the timers I will verify the gates I send are working.

p.p.s. I've sent this to the list, so if Dwight doesn't bite someone
else at a penurious school may.

Dwight K. Souder wrote:

Thank you for everyone who had responded. I figured that the rotational
inertia and friction would play a factor, but I was hoping that it wouldn't
play that big of a factor.

At my school, we don't have photogates...unfortunately. I was hoping to be
able to do without them.

I do like the idea of "Newton's golf" by John Denker
( and plan on testing out that
idea. Can anyone suggest where I might be able to find large metal ball
bearings? If I can't find metal balls, I may test it using golf balls. Any

I also like Stacy Kissel's suggestion of placing hoops through the path of
the projectile. That would be an interesting activity.

For those who do this lab (preferably without photogates), would you mind
emailing me your lab? If I do use it (or part of it), I do give credit to
those people. My direct email is:

Also, if anyone is looking for ideas of some activities, check out my
website (below) and click on "Science Conference Lessons". These are just
some of the things we do in class.

Thank you and have a great day!
Dwight Souder

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