Magic Glass of Water

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Author: Melissa Bautista

Is the glass half full or half empty? When speaking in terms of matter the glass is always full. A drinking glass without water is said to be “empty”. However, air within the glass is the matter that fills up the glass. Using these concepts we can invert a glass of water without spilling a drop.


How does the phenomenon of the inverted glass of water serve as an example of the properties of pressure and surface tension?


  • Drinking glass
  • Piece of cardboard (4” x 4”)
  • Water 


This should be performed over a sink or outside.

  1. Fill a ¼ of the drinking glass with water.
  2. Place the cardboard over the rim of the glass making sure the mouth of the glass is completely covered.
  3. Place your hand over the cardboard and invert the glass. Keep your hand underneath the cardboard for at least 5 seconds.
  4. Slowly remove your hand from underneath the cardboard.
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