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Q & A: All about submarines

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Q:
I was wondering what Water pressure has to do with submarines and how a submarine works, not only its shape.
- Sarah (age 13)
Internation School of Geneva, Switzerland
A:
Many things go into making a submarine work.
Submarines are powered by some sort of power plant. In submarines used by the Navy the power comes from a nuclear reactor. In other submarines a regular diesel or electrical engine is used. These engines turn a big screw (propeller) which pushes the submarine forward. To turn a submarine has a rudder. The rudder is turned either right or left and that moves the water that is being pushed by the propeller causing the submarine to turn.
The next thing to think about is how do submarines go up and down. Well, submarines have what they call " ballast tanks " . These tanks fill up with water to sink the submarine. When the submarine wants to go to the surface the tanks are filled with air and the submarine goes up.
What does water pressure have to do with this? The deeper the submarine dives the more water pressure there is. In other words, as you go deeper there is more water pushing in on the submarines hull. This can be bad if the submarine goes too deep, since the hull of the submarine will break if the pressure gets too big.

(republished on 08/02/06)

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