Today, we were talking about floating and sinking. We conducted a simple investigation using water, lemonade and raisins to explore this concept further. We set up our equipment and recorded our observations on post-it notes. We discovered that raisins sink in water. However, in lemonade the raisins sink at first, then after a few seconds they float up to the surface, then sink again.
We discovered that this is because the raisins have more density than the water, so they sink to the bottom. Bubbles of fizzy Carbon Dioxide gas (in the lemonade) stick to the raisins, giving them extra buoyancy and causing them to float to the top. When the bubbles burst at the surface, the raisins sink down to the bottom of the bottle again. More carbon dioxide bubbles attach to the raisin, causing it to rise again. This process makes the raisins look like they are dancing in the lemonade.
Using our understanding of density and buoyancy, we tested a range of everyday objects from the classroom to see if we could recreate the dancing raisins effects.