suggested by Dr. Gordon Hamilton
Activity I
Demonstrating Glacier Flow
Materials: One recipe of 'flubber'
| Mix #1 | Mix #2 |
| 3/4 cup of warm water | 2 tsp of Borax |
| 1 cup of white glue | 1/2 cup of warm water |
| food coloring (optional) |
Procedure:
Stir
the mixtures separately until both are well mixed.
Pour mix #1 into mix #2 and a big glob of flubber
will form. Kids love this bit. Work it for 2-3 minutes
and drain any excess water. You can store it in ziplock
bags for a few months; just rework the liquid back
in each time.
Experiment:
Flubber
behaves just like ice. At low stresses it deforms
plastically. But at high stresses (like when you pull
it apart) it undergoes brittle failure. Ice deforms
plastically most of the time -- that's what allows
it to flow. When brittle failure occurs, crevasses
open up.
I like to let it flatten out from a round lump into
a flat pancake. I also have a 4" PVC drain pipe
that I cut in half lengthwise that I use to simulate
a valley. You can incline the pipe and see how fast
the flubber flows. Note that the flow is slower near
the sides of the pipe because of friction from the
valley walls. Or you can wet the pipe (the flubber
should flow faster because of less friction). Or you
can put one lump in the freezer for a while and compare
how fast it flows compared to a warmer piece of flubber
(warm ice deforms more easily than cold ice).
Or you can make a continent out of clay or papier
maché including mountains, cover it with plastic
wrap or foil and then try the 'flubber'.
Activity II
Sea
Level Rise
Materials:
Ice cubes
Fish tank or other large glass container
Experiment:
Sea level rise: a lot of people think that melting
icebergs cause sea level rise. Not so! You can fill
a fish tank with water and add some ice cubes. Note
the water level on the tank. As the ice cubes melt,
note the new water levels. They will be the same,
because the ice cubes have already displaced an amount
of water equal to their melted volume. Only grounded
ice (ice on land) that melts will cause sea level
rise. Try melthing and dripping the same amount of
ice cubes over the side into the tank. The water level
will go up.
Activity III
Ocean Circulation
Materials:
Ice cubes, some fresh water, some made with salt
Fish tank or other large glass container
Food coloring
Experiment:
Ocean circulation: ocean circulation (which in turn
drives atmospheric circulation and the re-distribution
of heat on planet earth) is driven by melting of Antarctic
ice. The process is called the "oceanic conveyor".
Cold fresh water from melting polar ice sinks to the
bottom of the ocean and forms an enormous submarine
current that travels through all the world oceans.
Without cold Antarctic water, this current would be
shut off and there would be enormous changes in climate.
You can see it in action by dropping ice cubes into
the fish tank. Use different food colorings for different
types of ice: freshwater ice and ice made with salty
water. The food coloring currents that form on the
bottom of the freshwater ice cubes will be much more
vigorous.