Date: Wed, 31 Mar 1999 16:35:59 -0800

Author: Kelly Victoria Beck

Subject: Re: Intro Lab Activities


Hi Paul,

Here are some answers to some questions about the lab activities. Kelly
>Question 1: What is gaffer's tape? I see gaffer listed on modern movie
>but have no idea what they do?

Basically, on a movie set, a gaffer is the person who does the lighting.
Gaffer's tape is a cloth tape, traditionally black, used in photography,
film, and stage lighting. It functions excellently in sealing light leaks.
It is strong like duct tape, but doesn't leave a sticky residue and can
easily be removed. I prefer this to duct tape, with one little problem -
$$$$ compared to duct tape.

>Question 2: Never having experienced one, I thought earthquake frequencies
>of the order of 1 Hz. How do you get a group of students to run in and out of
>the tower at such a frequency?

Although the students do indeed do this lab when studying faulting and
earthquakes, we don't necessarily care that they exactly simulate
earthquake frequencies. What we really want to get across is the idea of
the effect of earthquakes on structures taking into account a particular
structure's resonance and the difference between p and s waves. It's also
no problem to have students pivot on their heels against and away from the
building at 1 Hz. But we often don't talk about frequency of an
earthquake, but amplitude, i.e. the richter scale.

>Question 3: What do the facility engineering folks think of this little
Nobody has complained yet. Evidently, before my time, geology classes used
to do this with the much taller, much more historically significant Hoover
Tower on campus.

>Question 4: Where do you get fresh (unreserved in formaldehyde) cow eyes?
Talk to your local butcher. They can probably get the eyes for you on
special order. We get our eyes from a butcher that serves the metropolitan
Bay Area scientific needs for fresh meat parts - cow and pig hearts and
plucks for educational/scientific dissection. They get their eyes from
beef slaughter houses. By the way, this sort of graphic talk reminds me
that we do not require students to do this lab - some are sickened by it,
some have moral objections. Ultimately, almost all of our students do this
lab and love it. The Exploratorium has step-by-step instructions of their
version of the cow eye dissection on their web page.

>Question 5: How do students measure a TV ghost image? Do they measure
>between strong and weak images on the screen or period of flicker or what?
They measure the distances between two identical points on the strong and
weak images. Phys. Teach., Vol. 23, No. 6, September 1985 Pages 360 - 360
is a good reference.

>Many other questions come to mind. Perhaps you can post write-ups of and
>problems you have experienced with these experiments.
>I teach physics and physical science at Collin County College, a two-year
>college in the northern suburbs of Dallas.