Challenge: Science Experiment

Science in the Kitchen:  Keeping Dry in Water

This fun little experiment is almost like magic!  Learn how to keep a tissue dry in water.

Materials:

  • Mug or opaque cup or glass
  • Clear cup or glass
  • Paper or plastic cup with a whole in the bottom
  • Paper towels or tissues
  • Container of water

Procedure:

  1. Stuff a paper towel or tissue into the bottom of the mug so that it won’t fall out if you turn the mug upside down.  Turn the mug upside down and submerge it in the water.  What do you think you will find when you pull it back out?
  2. Was your paper towel dry?!  How did that happen?  To get a better look, try again, but use a clear cup or glass.
  3. What do you think will happen if you tilt the cup while it is under water?
  4. What do you think will happen if you use a paper or plastic cup with a hole in the bottom?

How it works and real-life application:

Atmospheric pressure is the pressure exerted by the weight of air in the atmosphere of Earth. It is a considerable force, but one we barely notice because air exerts its pressure on us equally from all directions.

The air inside the inverted glass is at atmospheric pressure. When you submerge the glass, the air inside exerts enough pressure on the water to keep it from entering the glass.  Diving bells used in deep sea diving rely on the same principle to transport divers beneath the sea.

Sources:

http://www.learnplayimagine.com/2014/06/how-to-keep-tissue-dry-in-water.html
http://www.terrificscience.org/lessonpdfs/TissueinaCup.pdf