As part of our Unsinkable topic, we carried out the Cartesian Diver experiment. We had to create a floating object using a straw, paper clip and Blu Tac. Firstly, we had to test whether our object was able to float in water then we filled a plastic bottle with water, popped our ‘diver’ in and screwed the lid on. We were hoping that, by applying and releasing a little pressure on the bottle, our diver would sink and float.
We had to make a few changes to our diver in order to get this working properly. We learned that our Blu Tac couldn’t touch the straw, we needed quite a lot of Blu Tac and we didn’t need to have our bottles completely full of water.
This experiment helped us learn about buoyancy. As we applied pressure to the bottle, the air bubble in the straw decreased in size so the diver became less buoyant and began to sink. As we released pressure on the bottle, the air bubble increased in size and began to float again.
We all worked hard to improved our diver designs and many of us got our Cartesian Divers working!
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