You can learn about three forces — gravity, adhesion and cohesion — with one nifty experiment! You see, water molecules are attracted to each other. This is called cohesion. Water molecules are also attracted to other molecules, like the ones in the string. This is called adhesion. The force of gravity pulls the water down, and the water “sticks” to the string when you pour because of adhesion and cohesion. Go ahead, give it a try! It’s easy, and it looks pretty darn cool!
What You Need
- Small pitcher of water
- Food coloring
- Cotton string
- Paper towel
What You Do
- Add a few drops of food coloring to the pitcher of water and stir to mix.
- Cut a piece of string about 60 cm (2 feet) long.
- Soak the string in the colored water.
- Working over the tray, press one end of the string against the inside of the pitcher’s spout. Hold the other end of the string against the inside of the cup. Make sure you pull the string so it is tight.
- Position the pitcher higher than the cup and carefully pour. Can you get the water to pour along the string and into the cup?
Mad Science of Austin’s mission is to spark the imagination and curiosity of children by providing them with fun, hands-on and educational activities. Central Texas youth have been “edu-tained” with their week-long science-themed camps since 1997.