Question: Can You Measure Surface Tension of Water With a Penny?

Did you know that even though water is a liquid, it isn't always able to get into little cracks and crevices? So how do clothes go from caked with mud to clean? How can dishes go from greasy to glistening? With a few simple household items, you can find out!

Materials Needed:

(Any of The Materials Highlighted in Blue are Clickable Links for Purchasing)

Tap Water

Dish Soap

Drinking Glasses


Dropping Pipet


Paper Towel

Lab Notebook


Project Procedure:

1. Create a table in your lab notebook like the one below.

Type of Water Trial 1 Trial 2 Trial 3 Average
Regular Water
Soapy Water


2. Fill a glass with tap water

3. Fill a second glass with tap water. Add a few drops of dish soap and mix gently with a spoon

4. Use the bulb on the Pipet to suck some of the plain tap water into the Pipet

5. Place your penny on a flat level surface 

6. Use the Pipet to drop one drop of water onto the center of the penny

7. Continue slowly adding drops until the bubble of water on the penny bursts and spills over the edges.

8. Make sure and record the number of drops it took before the bubble burst

9. Dry off the penny and repeat steps 5-7 twice. Record the number of drops in the table each time

10. Repeat steps 4-7 with soapy water. Again, be sure to record your data in the table

11. Calculate the average drops it took for each of the two kinds of water

12. Based on the number of drops for each attempt, do you think adding soap increased or decreased the surface tension of the water?

Posted by Isaac Fornari on 13 February, 2017 elementary, physical science fair projects |
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