# 2B40.59 - Density Ball, Rods, Galilean Thermometer, Eggs

Code Number:
2B40.59
Demo Title:
Density Ball, Rods, Galilean Thermometer, Eggs
Condition:
Excellent
Principle:
Comparison of Densities
Area of Study:
Heat & Fluids
Equipment:
Density Ball, 2 Beakers, 2 Thermometers, Hot and Cold Water, Density Rod, and Reverse Density Rod.
Procedure:

Take cold water directly from tap (about 22º C), and place in one beaker.  Place warm water (about 35º C), in the other beaker.  Insert the thermometer probes to monitor the temperatures.  When you place the density ball into the cold water it should just barely float.  When placed in the hot water the density ball should sink.

The density rod is designed to show the same effect as the density ball described above.  That is it will float in cold water but sink in hot.

The reverse density rod will show the opposite effect.  That is it will sink in cold water and float in hot.

Another example of this would be the two balls that have equal masses yet one floats and one does not due to different volumes.

References:
• Martin Gardner, "Two Stunts with Eggs", TPT, Vol. 37, #4, Apr. 1999, p. 245.
• Dick Heckathorn, "A Density Demonstration", TPT, Vol. 25, #1, Jan. 1987, p. 39.
• Linda L. Maier, "Eggs—Sink or Float", The Science Teacher, Vol. 56, #4, Apr. 1989, p. 68.
• "F-135. Plastic Ball in Salt Solution", DICK and RAE Physics Demo Notebook, 1993.
• Rick Beyer, "Bath Time", The Greatest Science Stories Never Told, p. 2.
• Joey Green, "Floating Egg", The Mad Scientist Handbook 2, p. 37.
• H. J. Press, "133. Suspending an Egg", Giant Book of Science Experiments, p. 144.
• Janice VanCleave, "87.On Top", Janice VanCleave's 204 Sticky, Gloppy, Wacky, and Wonderful Experiments.

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