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Code Number: 2A10.15

Demo Title: Submerged Float

Condition: Excellent

Principle: Surface Tension

Area of Study: Fluids

Equipment: 

Submerged float apparatus, Plexiglas box with water.

Procedure:

The device is weighted so that it floats halfway out of the water.  If you press the device into the water and release slowly the surface tension on the circular wire at the top will hold the device under water.  Breaking the surface tension will allow the device to float halfway out of the water again.  The surface tension can be broken by adding a drop of soap or by blowing into the circular wire/water surface.

References:

  • W. C. Thoburn, "The Origin of Surface Tension in Liquids", TPT, Vol. 15, # 4. Apr. 1977, p. 234.
  • J. Pellicer, V. Garcia-Morales, L. Gaunter, M. J. Hernandez, and M. Doiz, "On the Experimental Value of the Water Surface Tension Used in Some Textbooks", AJP, Vol. 70, # 7, July 2002, p. 705.
  • S. Y. Mak and K. Y. Wong,  "The Measurement of Surface Tension by the Method of Direct Pull",  AJP, Vol. 58, No. 8, August 1990.
  • George M. Hopkins', "Submerged Float", Experimental Science, Volume Two, p. 229. 
  • Martin Gardner, "A Water Transfer", Science Tricks, p. 11