Hey Ray! Playing Around With The Density Equation

PITTSBURGH (KDKA) -- We have done a lot of experiments and covered a lot of topics. This time, we are going to play around with density, and use its ingredients to make some weird science.

We have talked about density before. Remember, if an object is denser than what is surrounding it, it will sink. If it is less dense than what is surrounding it, it will float. Since density is mass per unit volume, we draw the equation this way.

I know some may not like math, but this equation gives us hints as to how we can control how certain things act. When you have an equation like this, it is a way of saying density and volume have an inverse relationship. If you increase density, the volume decreases. If you increase the volume, the density decreases. Let's show this as an experiment.

All we need is a plastic bottle filled to the tippy top with water, and a ketchup packet. Put the ketchup packet, or other condiment packet, in the bottle and put the lid on, and observe what is happening. You should see the ketchup packet floating to the top.

Now, squeeze the bottle. The packet should sink!

You didn't add anything to the bottle, so what is going on here? You must be doing something to increase the density of the ketchup packet, though.

Squeezing the bottle causes the volume to decrease. When the volume decreased, the density is increased, like the equation.
Since we filled the bottle to the tippy top, that means there is no air in the bottle, aside from the little bit of air that is in the ketchup packet. In the bottle it floats until you squeeze the bottle. When you squeeze the bottle, the water squeezes the ketchup packet. This compresses the air in in the packet, so it can't take up as much space, making the packet denser than the water, causing it to sink.

And when you stop squeezing the bottle, the opposite becomes true.

This is one of those science experiments that you can treat like a magic trick, too. Especially if you pretend to make the packet float and sink with your mind.

Tips To Make This Work Better:

• Check the condiment packet to make sure it floats before you start the experiment. You may want to check a few packets and choose the one that floats best. If the packet doesn't float to begin with, this experiment will not work.
• If the bottle is too small, this experiment may not work as well either. I used a 2 Liter bottle for my version.
• Clear bottles make everything easier to see.
• Make sure to recycle all recyclable parts of this experiment when done!