They have huge lungs
No. I thnk you have been waching the wrong movies.
A nuclear powered submarine can remain submerged for as long as it has fuel rods and supplies for the crew.
The Wrathful. They must fight each other on the surface of the Styx, comprised of acrid mud, while the Black Cherubim keep them submerged in the mud below.
Cactus is not an aquatic plant, it grows in the desert, so the problem of remaining afloat does not arise.
Because amphibians largely dwell in aquatic habitats and have highly permeable skin, requiring them to remain near a water source so that they don't dehydrate. Their habits make them amphibious, because while they live in the aquatic habitat, they can come onto land for short periods. They are not reptiles, but are classified as herptiles however, and so they fit within the study of herpetology.
They will become atrophied
Remain empathetic and express concern
The main one is these submarines can effectively remain submerged (and thus hidden) all the time. They are only really limited by the amount of food they can carry for the crew.
A body whose total density is greater than that of water will sink in water;that is, if it's not supported, it will continuously drift lower.A body whose total density is less than that of water will float in water; that is,it will sink only partially, and will then remain on the surface and sink no lower.A body whose total density is exactly equal to that of water will have "neutral buoyancy",and will "float submerged" so to speak. That is, none of it will remain above the surface,but once submerged, it will neither rise nor sink further, but will maintain the depth at whichit is placed.
The question cannot be answered because it is based on a false premise: the number of elements does NOT remain fixed.
After over 100 years of being submerged at the bottom of the Atlantic Ocean, human remains have by all accounts deteriorated where the only evidence that they were there are pairs of shoes and clothing.
The time period of a vibrating swing will remain constant by addition of more weight because time period depends upon the length of the pivot or string to which the mass (bob) is attached. Period of the swing is independent of the mass of the bob.