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Why can I see patterns in the water?
Normally, you can't see how the water is moving
inside a full jar of water. Water that's moving in one direction
looks the same as water that's moving in another direction. But
glycol stearate, the chemical that gives some liquid hand soaps
a pearly look, lets you see patterns flow in water.
What kinds of patterns can I see in my jar?
Who cares about these patterns?
When you turn the bottle slowly, you'll probably
see smooth streaks in the water. When layers of water are moving
slowly and smoothly past each other, you get this pattern, which
scientists call laminar flow.
When you suddenly stop turning the bottle, or
when you turn it very fast, you may see lots of swirls and wavy
patterns. When one layer of water moves rapidly past another layer
of water, it causes turbulence, which you see as swirly patterns.
When people design airplanes, cars, boats, golf
balls, and other things that move through air or water, they study
the patterns blowing air or flowing water makes as the object
moves through it. Differences in the flow of air or water can
affect how well an airplane flies, how much mileage a car gets
per gallon, how fast a boat can go, or how far a golf ball will
fly when you smack it with a club.
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Fill
the bottle or jar about 1/4 full with liquid soap. Add a drop
or two of food coloring. The coloring will make the swirls easier
to see.
Turn
on your faucet so you have just a trickle of water. Use that to
fill up the rest of the bottle. (If you run the water too hard,
you'll get foam.) Make sure that the water fills the bottle all
the way to the very top.
Screw
the cap on the bottle. Turn the bottle upside-down a few times
to mix the soap and water. If you get foam, take the cap off and
trickle some more water into the bottle. The foam will run over
the edge. Recap the bottle tightly.
Dry
the bottle and the cap, then wrap clear tape around it so the
bottle won't leak.
Twirl
the bottle slowly. What do you see? What happens when you stop
twirling the bottle? What happens if you spin it quickly?
Try
shaking the bottle up and down or side to side. What different
patterns do you see inside the bottle?
If
the liquid inside the bottle looks like it's all one solid color,
just twirl or shake it again to make more patterns. If the cap on
the bottle is sealed, Go with the Flow can last for years
