Submarine operation

Submarine operation

Submarines submerge and surface by changing the average density of the hull.

Physics

Keywords

submarine, lift, Archimedes' principle, floating, submersion, gravitational force, watercraft, airlock, density, descending, rising, average density, air, sub, fluid, sluice, mechanics, physics

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Cutaway

• ballast tanks - When the submarine [b]rises[/b], compressed air is pumped into the ballast tank, which causes water to discharge through the open lower valves. Therefore, the overall density of the submarine decreases and the boat ascends. During [b]submersion[/b], both the upper and lower valves are open. Water entering from the lower valves vents the air, which leaves the tanks through the upper valves. The overall density of the submarine increases and the boat submerges.
• compressed air
• buoyant force - It acts on submerging objects and depends on the volume of the object's immersed portion. That is, when the submarine sinks, the buoyant force increases until water fully covers the boat. The boat has to overcome it by increasing the weight.
• gravitational force - The submarine's weight increases by flooding the ballast tanks. When the weight exceeds the buoyant force, the boat descends. When the buoyant force is greater than the weight, the boat ascends.

Animation

• ballast tanks - When the submarine [b]rises[/b], compressed air is pumped into the ballast tank, which causes water to discharge through the open lower valves. Therefore, the overall density of the submarine decreases and the boat ascends. During [b]submersion[/b], both the upper and lower valves are open. Water entering from the lower valves vents the air, which leaves the tanks through the upper valves. The overall density of the submarine increases and the boat submerges.
• compressed air
• buoyant force - It acts on submerging objects and depends on the volume of the object's immersed portion. That is, when the submarine sinks, the buoyant force increases until water fully covers the boat. The boat has to overcome it by increasing the weight.
• gravitational force - The submarine's weight increases by flooding the ballast tanks. When the weight exceeds the buoyant force, the boat descends. When the buoyant force is greater than the weight, the boat ascends.

Principle of operation

• buoyant force - It acts on submerging objects and depends on the volume of the object's immersed portion. That is, when the submarine sinks, the buoyant force increases until water fully covers the boat. The boat has to overcome it by increasing the weight.
• gravitational force - The submarine's weight increases by flooding the ballast tanks. When the weight exceeds the buoyant force, the boat descends. When the buoyant force is greater than the weight, the boat ascends.
• overall density is greater than that of the surrounding water = submersion
• overall density is less than that of the surrounding water = rising
• overall density is equal to the surrounding water = floating

Narration

A submarine is a watercraft capable of traveling underwater.

When a submarine submerges, valves are opened, filling the hull with water. Because of this, the weight, and therefore the density of the hull increase. A buoyant force acts on the submerged bodies: If the force of gravity exceeds the buoyant force the boat starts to sink.

When a submarine ascends, water is pumped with compressed air from the water tank and discharged through the valves. This is why the weight of the boat decreases. If the force of gravity is lower than the buoyant force, the boat ascends.

Although submarines can perform a variety of tasks, they are most important in military operations. Today’s military submarines are designed to launch cruise missiles and ballistic missiles: the latter played an important role during the Cold War in nuclear deterrence and, thus, in maintaining peace.

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