PURPOSE: To demonstrate the change in the density of water with temperature.

DESCRIPTION: A calibrated thin spherical metal shell with air and shot inside sinks in water at 115 degrees F. The water is then cooled by a fan, whereupon the sphere rises to the top of the water when a temperature of about 110 degrees F is reached. The water can be stirred continually to keep the temperature uniform using the digital thermometer probe, which simultaneously reads the temperature, which is displayed on a large scale. If the sphere starts out floating and is sunk by heating the water, the demonstration requires more time due to surface tension.

SUGGESTIONS: BE CAREFUL with sphere - it is carefully calibrated.

REFERENCES: (PIRA unavailable.) See Demonstration Reference File for further information.

EQUIPMENT: Calibrate sphere in beaker of warm water, digital thermometer, and fan.

SETUP TIME: 5 min.

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