Why Does A Submarine Float And Then Sink?

A submarine floats on the surface due to the fact it displaces more water weight than what it weighs when its ballast tanks are filled with air. Once the ballast tanks are filled with water then the submarine weighs more than the water it is displacing causing it to sink. Much of the vertical movement of a submarine can also be attributed to the action of the bow planes which act like wings in the water to provide the submarine manuverability while it is underway.

A submarine floats and sinks because it has special air function that causes the pressure to way it down to sink and keep it up with less pressure.

Subs have ballast tanks. When they want to submerge, water is pumped into the tanks. When they want to surface, air is pumped into the tanks, expelling the water and making them buoyant.

Here is a great example:

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This boat emptied its balast tanks to get rid of organisms living in the water and it all went wrong.

Submarines are ideal for use at great depths. Thanks to their firm, double-walled hulls, people inside are able to live in good health and work as usual as long as there is air and power supply. Submarines are operated by turning the rudder left and right. A propeller is used to move the submarine by pushing against the water and creating an upward thrust. The reason why a submarine doesn't sink is because its metal hull has a volume around it, which is less than an equal weight of water displaced.

Submarines explain the concept of buoyancy. They are built with buoyancy tanks which can be filled with varying amounts of water or air. The more is the air filled in these tanks, the more is the buoyancy of the submarine. When the tanks are full of air, the submarine weighs less than the volume of water it displaces and floats. When the ballast tanks are flooded with water, the submarine weighs more than the water displaced and it stays underwater.

Basically it has several compartments full of air that help it float...but when it needs to dive it fills these compartments full of water and the sub begins to dive (or sink)

Because      it has ballast tanks wich fills with water and then it sinks

Got a few light people on board floats then a fatty gets on and it sinks

The way a submarine sinks is, there are valves on it that allow water in to the ballast tank. The more water in the ballast tank the faster the submarine will descend into the ocean. To surface, the core of the submarine lets out air into the ballast tank making the water rush out of the flood ports making the submarine more buoyant. This buoyancy will allow the submarine to ascend to the surface

Tell me know how a submarine sink ok get it