COUNTY SLIGO SEO CONTAE SHLIGIGH 2002 A.D.

 

EXPERIMENT NO. 11: SURFACE TENSION We notice that some insects can trot along the surface of water without sinking or splashing water about. We believe this is because they are very light and therefore do not break the "skin" on the top of the water. This is because of surface tension. (Save this page and  print it out. Then do the experiment, and write your own report.)

Laboratory: Stokane National School Date: 27th March 2002 Objective: To investigate surface tension Apparatus: Tumbler, water, pieces of card or plastic, pen Method: Almost fill the tumbler with water, and gently place a dry piece of card or plastic on top, so that it floats. Gently force the centre of the card downwards a little and notice the water at the edges of the card curves downward, under the card, as if the water were jelly-like.

Surface tension in tumbler of water

LINKS

http://hyperphysics.phy-astr.gsu.edu/hbase/surten.html http://library.thinkquest.org/2690/exper/exp12.htm

REPORT We filled a tumbler with water almost to the top and gently placed a piece of a cheese box on the surfaceof the water. We gently pressed on the centre of the piece of card with a pen, and as the card moved downwards we noticed that the surface of the water did not break. We also noticed that it appeared as if the edges of the water around the card were jelly-like. We pushed harder and the surface broke. The card then got soggy and we had to use a fresh piece of card. We found that a glossy card could be used many times. We tried milk and the result was the same. We went to Encarta and read up on surface tension, and creatures that rely on it for movement. CONCLUSION Surface tension exists on water and milk and this allows some insects walk on the surface of water without sinking. It probably exists on other liquids too.

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