20,000 PROBES UNDER THE SEA
The deep ocean is no longer mysterious and unknown. That's because in recent years, scientists have used all sorts of research tools including robotic and piloted craft to explore this hidden realm. And we are about to learn more about the ocean. A new generation of probes, data cables, piloted submersibles and a robot capable of roaming the sea for years is about to join oceanographers' arsenal of research tools.
by Michael DiSpezio
published online September 19, 2005
Ascending Submersible
Many submersibles depend upon a change in buoyancy in order to ascend or descend in the ocean. Often, this change is accomplished by using ballast tanks. When filled with water, these containers have a negative buoyancy due to the weight of the water inside. When air displaces the water, the tanks become lighter and take on a positive buoyancy. In this activity, you'll model what happens when air replaces water with a model of a ballast tank.
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Plastic film or medicine container (clear plastic works best)
Effervescent tablet
Large bowl
Waterproof clay
Water
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CAUTION: Address any safety hazards associated with the use of effervescent tablets. |
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|  1. Shape a collar of waterproof clay around the "lip" of a film canister. 2. Fill a deep bowl or basin with tap water. 3. Place an effervescent tablet into the canister. 4. Put the canister in the bowl, allowing it to fill with water. 5. Position the canister upside down on the bottom of the bowl. 6. Observe the action of the tablet and any related movement of the canister. |
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