Theory Thursday: Soy Sauce Submarine

 I don't know about you but when I was a kid I always loved playing with stuff that floated in the bathtub. I had this little wooden boat that I played with all the time. My dad had made it for me, it was just a basic boat shape cut from plywood with a dowel sticking out the middle and a piece of material that hung off the dowel as a sail. How many of us threw rocks in any body of water we had the chance to, I still do! We love playing in the water. There is something intriguing about seeing what floats and sinks. How about something that floats and sinks?

All you need is a bottle full of water, Soy sauce packet (or any plastic condiment packet), and a small paper clip or two.

Attach the paper clip to the bottom of packet and insert in the bottle.

It should float at the top of the bottle. If it floats with a lot of the package above the surface of the water add another paper clip or upgrade to a large paper clip. Do yourself a favor though, don't start with a large paper clip. It just might be too heavy and sink. Then you have dump all the water and fish the packet back out. I won't mention how I know this.

With your sauce packet now floating at the surface begin to squeeze the bottle.

Isn't that cool! So.... do you wanna know how it works? We all know that water is less dense than air that is why it "floats" above the water in the bottle. Well the air in the sauce packet keeps the packet afloat. When you squeeze the bottle the air and water have no where to go so something has to give. Since water does not compress as air does the water compresses the air. When the air inside the packet gets compressed to the point at which it is denser than the water outside the packet the packet falls. When you release your squeeze all returns to normal and the packet floats.

Well, don't just watch our video. Go make your own see how hard you have to squeeze the bottle. Can you squeeze hard enough to get the air in the packet to lay the packet down? Or can you get the packet to float in the middle? Make it a game, who can get the packet to float in the middle the longest? Just go try it and have fun!