How do submarines go underwater and float up?

A submarine (or any boat) can float when the mass of water that it displaces (pushes out of the way) is equal to the mass of the boat. This displaced water causes an upward force called buoyancy. To control its buoyancy, the submarine has ballast tanks (see picture) that can be filled with water or filled with air.

How does a submarine manage to rise up and move down in water?

When the ballast tanks are filled with air, the submarine rises to the surface because it has positive buoyancy. With water inside the tanks, the sub has negative buoyancy so it sinks deeper into the ocean.

How a submarine can submerge or float itself in the ocean?

A submarine or a ship can float because the weight of water that it displaces is equal to the weight of the ship. To control its buoyancy, the submarine has ballast tanks and auxiliary, or trim tanks, that can be alternately filled with water or air (see animation below).

How do submarines sink for kids?

To sink, a submarine must weigh more than the water it displaces – this is called a negative buoyancy. So to get it to weigh more, special tanks are flooded with water. This makes the sub heavier and so down she goes. And when they want to go up, they need to make the sub lighter.

What happens to a submarine when it submerges?

The submarine becomes denser (heavier) in relation to the ocean, and submerges. When the time comes to surface, the vents are closed, and the seawater in the ballast tanks is expelled with pressurized air. The vessel becomes lighter (less dense) relative to the surrounding water, and thus buoyant.

How do you control the buoyancy of a submarine?

To control its buoyancy, the submarine has ballast tanks and auxiliary, or trim tanks, that can be alternately filled with water or air (see animation below). When the submarine is on the surface, the ballast tanks are filled with air and the submarine’s overall density is less than that of the surrounding water.

How do submarines dive so fast?

The angle of these ‘wings’ directly influences the speed of the dive. On the other hand, when a submarine has to resurface, compressed air is blown into the ballast tanks from air flasks, which pushes the water out of the tanks at a rapid rate. This results in a decrease in the overall density of the submarine, causing it to rise to the surface.

How does a submarine float on the surface?

When a submarine needs to return to the surface, compressed air stored in tanks is blown into the ballast tanks. This air forces out the seawater, and the vessel begins to rise, aided by the hydroplanes. Once again lighter than the seawater it displaces, the submarine is able to float on the surface.