Kate's Corner: Sinking Ketchup

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BRIDGEPORT, W. Va. (WDTV) - Want to magically make a ketchup packet sink to the bottom of a water bottle by doing just one thing? Well, all you need for this one is a packet of ketchup from your favorite drive thru, a plastic one liter bottle, and water.

First we are going to test our packets and find one that just barely floats. Then put that packet into your liter bottle. Fill that bottle all the way to the top and put the lid back on.

Now that you are all set up, we are going to get the packet to go to the bottom of the bottle without flipping it. How do you do that?

All you have to do is squeeze. The packet falls to the bottom when you squeeze it but the moment you release, it floats right back to the top.

Why is that? I'll give you a hint. It has to do with buoyancy and density.

It is not just ketchup inside the packet. There is also a pocket of air. When you squeezed the bottle, you compressed that pocket of air. This then makes the packet denser and therefore sinks to the bottom.