======Upside Down Water Glass======


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**Materials: **{{$demo.materials_description}}\\
**Difficulty: **{{$demo.difficulty_description}}\\
**Safety: **{{$demo.safety_description}}\\
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**Categories:** {{$demo.categories}}
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**Alternative titles:** Air Pressure Water Trick, Defying Gravity
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====Summary====                   
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====Procedure====  
  - Fill a drinking glass completely to the brim with water. (If the glass is not full, the experiment won’t work.)  
  - Place a stiff sheet of paper (such as poster board) over the mouth of the glass.  
  - Move the glass over a sink or large container to prevent spills.  
  - Hold the paper firmly against the glass with one hand and quickly invert the glass.  
  - Remove your hand from the paper. Observe how the paper stays in place, preventing the water from falling.  




====Links==== 
Upside Down Water Glass Science Experiment - Cool Science Experiments Headquarters: 
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upside down water glass physics - Homemade Science with Bruce Yeany: 
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📄 Upside Down Glass of Water Science Experiment - Cool Science Experiments Headquarters: [[https://coolscienceexperimentshq.com/upside-down-glass-of-water-experiment/]]\\


====Variations====
  * Try using different types of paper (thin paper, cardboard, or plastic sheets) and compare results.  
  * Test with different glass sizes and amounts of water.  
  * See how long the paper can hold before becoming saturated and falling.  
  * Add food coloring to the water for visual effect.




====Safety Precautions====
  * Perform over a sink or container to catch spills.  
  * Use sturdy paper to avoid sudden collapse.  
  * Handle the glass carefully to avoid dropping and breaking.





====Questions to Consider====
  * Why doesn’t the water fall out of the glass when upside down?  
  * What role does air pressure play in holding the paper in place?  
  * How heavy is the air pressing upward compared to the weight of the water?  
  * Why does the paper eventually fall after a while?  
  * Can you think of real-world examples where air pressure prevents liquids or gases from escaping?