Nils: So this is a lab I learned in Buffalo State University I think from
Lowel Sylvester, so i think he's the creator of this.
Anyway the puzzler is we have an action-reaction platform here with
a stretched rubber band
held back with a string, and we're going to burn that string
with a lighted match.
We're going to put the ball in here,
and then we're going to
do the same thing again, shoot it again
but this time with a metal ball. And so the question is...
which one will have more recoil?
With the wooden ball?
Or with the metal ball?
So, let's load this up and
see what happens!
Ready?
Nice. So the answer is... when you have a heavier ball in there
you get more recoil.
So the question is—and we
pose it to the students—
can we predict this? how do we predict this? What are the variables
that we have to deal with?
How do we isolate these varaibles and how do we understand the problem?
So...that's for them to do!
ALLEN: And we've already tried to do it over here, right?
NILS: Yes, on the board we have our solution...[laughs]
ALLEN: Yeah, it's not trivial...
NILS: It's not trivial, but uh, you know...
We came up with some analogies, like standing on roller skates and pushing
against a brick wall,
or standing on roller skates and pushing a little kid [laughs]...
you can kind of think of the reaction
that would happen to you...
This is just uh...high strength fishing
line—it's like a thread
uh... this is some Masonite,
with just
screws and nuts on the bottom side
I just drilled holes for the bolts...
I put a washer in there to reduce the stress on the wood,
and a clothespin so...it's pretty basic.
Oh, the balls—
this one is just a generic steel ball bearing, and this came from a crafts supply store,
and I chose these just beacuse they're approximately the same diameter,
so they would shoot in a similar manner.
So, on the computer,
we were able to load the videos in there,
and from here we can actually track it,
so we'd be able to watch the video
and actually track its motion using this tracking software (Logger Pro)
I think there's another one for free online...
This made it simple to actually
put numbers onto the problem.
It appeals to certain students in terms of a film aesthetic (getting the lighting right),
so yeah it definitely interests and grabs attention of some students who
otherwise would be a little bit
...withdrawn from the activity.
So...lots of different things to do, in terms of
taking data, setting it up, analyzing the data, videotaping...
So...I think it's a pretty engaging lab activity and that's
what we're aiming to do, is to engage students in science.
So hopefully this will do it!