"solid" "fluid"; "fluid" "liquid". , , , . SOLID - a firm substance; not liquid or a gas. FLUID - able to flow easily, like water or a gas, not solid, as fluid substances. LIQUID - a substance that is neither a solid nor a gas, e.g. Air is a fluid but not a liquid. Water is both a fluid and liquid.
"solid" - , () Fluid . . "fluid" liquid .
TEXT
1. All matter is made up of solid, liquid, or gas or a combination of them. Since the transfer processes are affected by the medium in which the changes occur, it is imperative to understand the characteristics of each state.
2. A solid is generally thought of as a substance which offers resistance to change of shape (deformation), whereas, a fluid will deform continuously when subjected to a shearing stress, no matter how small. The mode of resistance distinguishes between a solid and a fluid.
3. A fluid may be either liquid or gas or a combination of the two. Fluids conform to the shape of their container. A liquid has a free surface, but a gas fills the entire container and has no free surface.
to conform - to compress - shape - substance - compressible - medium - (.. media) incompressible - |
4. We readily think of water and air as fluids, but many other substances which behave quite differently are also fluids, e.g. asphalt, glass. Blood is a fluid whose behavior varies widely, depending upon its content of hemocytes (blood cells), sugar, and plasma.
5. Fluids whose density changes are insignificant in a given process are said to be incompressible. Under normal conditions liquids are considered incompressible: gases and vapors may be compressible since their density may change considerably.
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TEXT C: UNITS AND DIMENSIONS
1. :
) "dimensions" "unit";
) .
A set of basic entities expressing our observations of the magnitudes of certain quantities is known as a dimension. Many units can be used to describe a dimension. For example, 36 inches = 3 feet = 1 yard = 91.44 centimeters.
Inches, feet, yard, and centimeters are units, but they all represent a measure of length - dimension. In transport processes the basic dimensions are defined to be force "F", length "L", time "T", temperature "Q", and mass "M"
UNIT II