Pouring Water Down a String
Materials: ★☆☆ Easy to get from supermarket or hardware store
Difficulty: ★☆☆ Can be easily done by most teenagers
Safety: ★☆☆ Minimal safety procedures required
Categories: Fluids and Surface Tension
Alternative titles: Water String Trick, Cohesion and Adhesion Demonstration, Travelling Water
Summary
Water is poured from one container into another along a piece of string. The demonstration shows how the adhesive and cohesive properties of water allow it to cling to the string and flow downward instead of falling freely.
Procedure
- Cut a piece of cotton string or yarn about 60 cm long.
- Tape one end of the string to the inside bottom of a glass.
- Fill a measuring cup with water.
- Soak the free end of the string in the measuring cup for about 30 seconds until it is fully wet.
- Raise the measuring cup about 30 cm above the glass, holding the string taut but not pulling it free or letting it touch the side of the glass.
- Slowly pour water from the measuring cup so that it travels along the string into the glass.
Links
Traveling Water Experiment | Cohesion and Adhesion in Water Explained | Science Experiment for Kids - Hungry SciANNtist:
Pouring water down a string experiment - Phil McCordic:
📄 Pour Water Down a String! - Blue Marble: https://thinkbluemarble.com/learning-galaxy/activity-lab/pour-water-down-a-string/
Variations
- Try using different types of string (cotton, nylon, wool) to see which works best.
- Test different string lengths to find the maximum distance water can travel.
- Change the angle of the string to compare how slope affects water flow.
- Try using a stirring rod to pour from one beaker to another (this is actually a technique use in science laboratories).
Safety Precautions
- Work on a waterproof surface or place a towel underneath to catch spills.
- Pour slowly to prevent splashing.
Questions to Consider
- Would water flow down a dry string? (No, because adhesion requires the string to be wet first.)
- How does the angle of the string affect the water’s flow? (Steeper angles generally allow smoother flow.)
- What happens if the string touches the side of the glass? (The water may run down the glass instead of along the string.)
- What property of water makes it stick to itself? (Cohesion.)
- What property of water makes it stick to the string? (Adhesion.)