Find out
what kinds of things bob in water and what things sink.
Discover
ways to make sinkers stay afloat.
Find out
what other liquids might change what floats and sinks
What you'll
need
bucket and smaller
containers (such as drinking glasses)
various fruits
and vegetables, eggs
small sports
balls
packing peanuts
or other foam scraps
tape
toothpicks
pens/pencils
journals
cameras
salt
vegetable oil
Getting
started
Predict which
of your objects will float and which will sink in a bucket of water. Write
your predictions in your journal.
Then test your
hypotheses. Were you surprised by any results? Do some things float better
than others? Do some heavier objects float and lighter ones sink?
Devise a way
to make the sinking objects float and floating objects sink.
Try adding a
good deal of salt to your bucket of water (or mix salt water in a smaller
container). Stir to make a solution.
Try floating
your objects again and see if you find different results.
Try floating
objects in a glass of vegetable oil. What's different?
Take pictures
of your devices that help objects float.
Can you do anything
to make the floating objects sink?
What next
Creation
and invention:
Create a density
column of liquids (oil, water, honey, corn syrup, rubbing alcohol, etc.) in
a clear soda bottle. Use food coloring to make the results more dramatic.
Try floating
an ice cube on the column. Where does it float? What happens when the ice
melts? What does this tell you about the density of ice? Can you get things
to float between the layers (try a LEGO block)?
Make a chart
of objects that float and sink, and in which liquids from your bucket or density
column tests.
Discussion:
What do people
use to float in water? How is this like your devices to make fruits and vegetables
float? Why do people float in water without the help of floaties?
What makes the
difference between salt and fresh water (or other liquids) as to what floats
in each?
What other sorts
of things are measured in density (population, air, bone)?
Field
trip possibilities:
Local
university chemistry lab to learn about experiments done based on density
Doctor's
office to talk about bone density
Population
studies center to discuss population density
