Special Thanks to Mr. Greg Labbe (for making the liquid nitrogen available) and to Mr. John Mocko (for making the pulley demostration equipment available).
Thanks to Mrs. Field and the students! I had a great time!
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The Aluminum Boat Experiment came to mind after I read "A Boatload of Pennies"
by R.E. Weston, Jr.
in The Physics Teacher, Vol. 40, Oct. 2002, pp. 392-393.
Here are copies of my handouts:
Sheet 1:
Introduction and Experiment
Sheet 2:
Data Sheet
Sheet 3:
Conclusions and Student Recipe for Liquid Nitrogen Ice Cream
The creative spirit of the students never ceases to amaze me.
The students were asked to give each boat a number or name, and here are
some of the results (with the creative spellings maintained).
Science Rules, Science Rules 2, Super Strong
sonik, speed
Sammy, Fruity, Crunchy
Carapathia, Titanic, Victory
floatsey, floater
sandy, puffy, floppy
float and sink #7, cousin pretty lean #9
Sea King, Bestop, onsinkable
The Roach, The Mosquito, The Wort
belly washer, I'm sinking!
Results: I combined all of the data (39 measurements reported
by the students) and got 0.45 +/- 0.15.
The typical mass
of a washer was 2.64 g.
When I converted
the data to be the density of the displaced fluid, the result was 1.19 g/cc.
Water has a density
of about 1.00 g/cc under the conditions of the experiment, so the class concluded
that
Archimedes was correct, at least to within their experimental uncertainty!
======================================
The Experiments with Pulleys did not have any sheets. Students worked
in groups of 2, and each team was given
some fishing line, some paper clips, and some fishing sinkers.
By looping the fishing line over a big binder clip
clamped to a desk, the students were directed to make different
"pulley" configurations. Although there is
friction when the line slides over the metal surfaces, the
students were able to understand the difference between
the use of a pulley to redirect the force and the use of the
pulley to gain a mechanical advantage. After this exercise,
studens had additional hands-on opportunities with real pulleys
and a rope with PVC demonstration.
