Word Usage – Do Submarines Float?

meaningverbsword-usage

Is it correct to say that a submarine floats if it is below the water surface?

According to the dictionary definition, it seems to me that this is a correct way to refer to a submerged submarine.

Merriam Webster – float: to rest on the surface of or be suspended in a fluid.
Oxford – float: Be suspended freely in a liquid or gas.
Oxford – float: Move or hover slowly and lightly in a liquid or the air.

The way I understand it, in a liquid or fluid means within the medium, not on the surface.
Is this the proper meaning?

Best Answer

Objects under water can float, rise or sink.

This is a Galileo-type thermometer:

fluid-filled cylinders with glass fluid- and air-filled bubbles floating at different levels

Depending on the temperature of the fluid in which the sealed glass fluid containing sealed bubbles are suberged, they will either rise, sink, or float at certain levels. Per Wikipedia:

The only factor that determines whether a large object rises or falls in a particular liquid is the object's density relative to the density of the liquid. If the object is denser than the liquid then it sinks, as it is heavier than the liquid it displaces. If the object is less dense than the liquid then it begins to sink until the weight of the displaced liquid becomes equal to the object's weight; then it floats at that depth.

So, yes, a submarine floats at a certain depth in the ocean. If it is to surface, it rises, or it sinks to a lower depth. It works on Archimedes' principle:

Archimedes' principle is the law of buoyancy. It states that "any body partially or completely submerged in a fluid is buoyed up by a force equal to the weight of the fluid displaced by the body." The weight of an object acts downward, and the buoyant force provided by the displaced fluid acts upward. If these two forces are equal, the object floats. Density is defined as weight per volume. If the density of an object exceeds the density of water, the object will sink. - Office of Naval Research