======Toppling Bottles======


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**Materials: **{{$demo.materials_description}}\\
**Difficulty: **{{$demo.difficulty_description}}\\
**Safety: **{{$demo.safety_description}}\\
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**Alternative titles:** Center of Gravity Demonstration
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====Summary====                   
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====Procedure====  
  - Add food coloring to water so the mass distribution is more visible.  
  - Fill one bottle completely with colored water, leave one empty, and fill another halfway.  
  - Tape a pencil to one end of a flat board to act as a stop.  
  - Place the three bottles in order (empty, half-full, full) against the pencil lip.  
  - Slowly raise the opposite end of the board until the bottles topple.  
  - Observe the order in which they fall.



====Links==== 
PRACTICAL: Activity to observe stability, tilting and toppling (with explanation) - Physics Rox: 
{{youtube>Oe1L34hvHzw?}}\\


📄 Toppling bottles - IOP: [[https://spark.iop.org/toppling-bottles]]\\


====Variations====
  * Try bottles of different shapes (tall vs. short, narrow vs. wide).  
  * Use sand instead of water for a different mass distribution.  
  * Compare stability on different surfaces (smooth wood vs. rough cardboard).



====Safety Precautions====
  * Perform on a stable, flat surface to avoid bottles falling uncontrollably.  
  * Use plastic bottles to prevent glass breakage.  
  * Clean up spills promptly to avoid slipping hazards.




====Questions to Consider====
  * Which bottle toppled first? (The empty and full bottles fell at the same time, while the half-full bottle remained upright longer.)  
  * Why is the half-full bottle more stable? (Its mass is concentrated lower down, giving it a lower center of gravity.)  
  * What is meant by the “center of gravity”? (It is the average position where the weight of the object acts.)  
  * How can you make an object more stable? (Lower its center of gravity or increase the size of its base.)