Biology
Mrs. Westphal
Name:______________________
Sinkin’ Lincoln
Have you ever accidentally overfilled a glass of water without it spilling? This is
due to water’s surface tension. Water has an incredible ability to stick to itself
(cohesion). Today, we are going to test the surface tension of water.
Objective:
 to define surface tension
 to determine what factors affect surface tension
 to collect data on how many drops of water a penny can hold
Materials:
 Pennies
 Paper cups with water
 Dropper bottles with clean water
 Dropper bottles with soapy water
 Paper towels
Answer the following questions before beginning:
1. What is surface tension?
2. How many drops of clean water do you predict a penny can hold?
(hypothesis) Soapy water?
Procedures:
1. Take your penny and rinse it well in the paper cup with clean water.
2. Dry it thoroughly
3. Place your penny flat on the table, heads or tails up.
4. Begin to add drops of clean water. Record # of drops.
5. Clean penny, repeat 2 more times.
6. Repeat with soapy water.
Biology
Mrs. Westphal
Name:______________________
Data:
Trial 1
Trial 2
Trial 3
Average
Class
Average
Clean Water
Soapy Water
Analysis:
1. Describe results using both your data and the class data?
2. How would you explain what happened?
3. Does the soap make a difference?
4. How do you think the results would change if we used quarters? Nickels?
Oil?
Conclusion:
Design another experiment that could be used to test the factors that affect the
properties of water. Be sure to include materials, procedures, and a data chart.