Yes they are, if they weren't then how would they be able to go into the fishtanks.
Pumps, buckets, tanks.
Yes, when a submarine boat pumps water out of its flotation (not floatation) tanks, the submarine should rise.
For the pumps
By their pumps and ballast-tanks: allowing water into the tanks to raise the vessel's density so can submerge, or pumping air into the tanks to displace the water and allow the submarine to surface.
Because the tanks are filled with air afterwards. Air has a lower density than water.
Because the tanks are filled with air afterwards. Air has a lower density than water.
Because the tanks are filled with air afterwards. Air has a lower density than water.
Because the tanks are filled with air afterwards. Air has a lower density than water.
Because the tanks are filled with air afterwards. Air has a lower density than water.
The water is replaced with air which is not as heavy as water for the same volume.
A submarine has a variable buoyancy due to it's ballast tanks. When a submarine submerges, it fills it's ballast tanks with water which causes negative buoyancy. When a submarine surfaces, it pumps the water out of the ballast tanks thus giving it positive buoyancy.
As with all boats, a submarine does not weigh as much as the amount of water it displaces. To go under the water's surface, it pumps water into special tanks (ballast tanks), and to rise up again those pumps force the water out of the ballast tanks and back into the sea.Ans 2 - Submarines can go deep and rise again by using water ballast and air pressure, as planned by the captain. -Unfortunately, when things go wrong, submarines DO sink.