As part of our ‘Unsinkable’ theme, we were investigating buoyancy today. We made a Cartesian Diver using a straw and paper clips. We had to check our diver floated in water vertically. Once we did this, we filled a plastic bottle with water and popped the diver into the bottle. We screwed the lid on tightly and applied pressure to the sides of our bottle by squeezing. The diver then sank to the bottom of our bottle. When we released the pressure, the diver rose to the top of the bottle again.
We learned that this is because we created an air bubble in our straw and when we applied pressure, the air bubble got smaller, therefore reducing the buoyancy of our diver. When we released the pressure, the bubble expanded, therefore increasing the buoyancy of our diver.
We had a lot of fun and didn’t get too wet! 💧
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