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Cartesian Diver 

To the left is a video of my professor explaining how to make your  very own cartesian diver!

Materials:

  • pipet

  • corrosion free nut

  • 2 liter bottle

  • water

The student becomes the teacher

Trick and  explain

How does the Cartesian Diver work:

Water is filled to the very top of the two liter. leaving very little air, if any at the top. 
When the bottle is squeezed, the air in the pipet is compressed making the pipet more dense than the water. 
Things that are more dense than water will sink; this is why, when squeezed, the dropper will sink to the bottom of the bottle. 
When you let go, the pipet is decompressed making it less dense, letting the pipet return  to the top of the bottle.

If you want to try this experiment out for your self here is a website where you can buy the materials for your classroom or just a trick to play on your friends and family. https://www.teachersource.com/product/cartesian-diversions-class-kit-only/density-divers

How to make Grapes float?

Materials:

  • grapes

  • salt

  • two glasses or bowls

  • water

How it works:

Grapes are denser than freshwater. That’s why they sink to the bottom when you put them in a glass of tap water.

Adding salt to the water increases the mass of the water without changing the volume too much. So the water becomes denser.  When you add enough salt, the water can become denser than the grapes. Therefore, grapes can float in the saturated salt water. This also explains why things float more easily in the ocean. The Dead Sea is famous for its extremely high density salt water and people can easily float in it without much effort.

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