What is needed

What to Do

What is Happening

When we do this, we see a lot of drops of root beer that float on top of the liquid in the cup. If we tap just right, we can get dozens of drops, some of which stay floating for several seconds.

So what is going on? To be honest, we don't really know. Here are some ideas that we have:

The real truth of the matter is, though, that we don't really know! We welcome your ideas.

Other Things to Try

Since this is one that we don't understand, there is room for experimentation. I think that this would make a cool science project. There are a lot of things you could test:

It's wide open, really. Share anything you find with us, and we will note your results on this page



1. What is it that is observed to floart to the top of the liquid in the cup?

2. What might be happening to the carbonation when you tap on the side of the glass?

3. How could the temperature of the drops change? Why would that have anything to do with floating?

4. Try floating warm colored water on colorless cool water and report your findings. What materials did you use?

5. Gas may form some sort of barrier in this experiment. Where does the gas come from, and what does it do?

6. Explain why hot tap water is cloudy.


Obtaining credit for your efforts

  • Print a copy of the blank laboratory write-up paper.
  • Read and complete each section, incomplete write-ups receive no credit.
  • Have your parent check your work and sign the paper.


The contents of the page was modified from that created for the
Little Shop of Physics, Colorado State University