Ask a submariner what he enjoys most about being in an underwater environment, and he’ll tell you about exploring new places and adventuring where no man or woman has gone before. In the spirit of all submariners, and of traveling underwater to new and exotic locations, you can begin to learn about buoyancy and how it affects an object’s ability to submerge in and emerge from a body of water by building your own test submarine. You’ll be able to prove that it is possible to alter the buoyant reaction of air in water.
- 2-liter plastic soda bottle with cap
- 6 condiment packets (such as ketchup, soy sauce or mustard)
Compare the current buoyancy of your test equipment by dropping the assortment of packets into a glass of water. Select the proper condiment packet by determining which packet doesn’t float too easily or sink too quickly. The proper condiment packet will be the one that is mostly submerged in the glass of water, but still floats near the top. It is this static buoyancy that will be perfect for your submarine.
Fill the 2-liter bottle to the top with fresh tap water. Have extra water on hand in case you lose water during the submarine testing, because a completely full diving arena is needed for your submarine to work.
Insert the condiment packet you chose into the bottle of water carefully, so that you do not puncture or damage the packet, rendering it useless. Once you have the packet in the bottle, make sure the bottle is still filled completely and seal tightly with the cap.
Test the law of buoyancy by squeezing the sides of the bottle gently with your open hand. Watch what happens. Does the condiment packet sink? Does it do nothing? By squeezing (and thus increasing pressure) on the sides of this full bottle of water containing your own submarine, you decrease the size of the air pocket in the condiment packet, causing the submarine to sink. When you release the pressure, the air inside the packet returns to its original size and the packet floats. This simple submarine demonstrates how many large-scale personal submarines alter their buoyancy enough to allow submariners to explore an underwater environment.