Allowing water into, or discharging it to replace by air, ballast-tanks built into the hull.
Ballast tank
Density is used in various practical applications such as determining the purity of substances, identifying materials through density-based separation techniques, and designing flotation devices for ships and submarines. Additionally, density is crucial in industries like aviation for fuel efficiency calculations and in construction for selecting materials with specific durability and weight requirements.
Control electronics are devices like remote controls. Control electronics are used to control other electronic devices
Aluminum
The density of any substance is constant, we don't control it. However, by finding the density of any substance, it can be used to help identify the substance.
They are devices that are used to control the flow of current.
During WW2, all the major countries involved used submarines.
mouse, keyboard, touchpad, pretty much something that is used to control your computer.
They were used by submarines to navigate when not in open waters, They were also used by submarines and anti-submarine ships to locate enemy submarines.
Submarines todaee are used for underwater exploration,funn,new life underwater.
Shallow diving submarines are used for reef watching in many parts of the world.
Nuclear energy is used to power most modern submarines