# Pressure and specific weight relationship

### Fluid Density Properties and specific weight

of gravity. The pressure in a static fluid arises from the weight of the fluid and is given by the expression Discussion. Fluid column height in the relationship. Unlike density, which has units of mass per volume, specific gravity is a pure Because the densities of all substances vary with temperature and pressure, the . 1 Molecular weight; 2 Critical temperature and pressure; 3 Specific Typical pressure/volume/temperature (PVT) relationships for a pure fluid.

For this reason, it is convenient to define the unit "lbm mol" as a mass of the material in pounds equal to its molecular weight. Similarly, a "g mol" is its mass in grams.

## Specific weight

One lbm mol or one g mol of any compound, therefore, represents a fixed number of molecules. The number of significant digits shown is the accuracy to which it has been determined experimentally. Any combination of temperature, pressure, and volume above that line segment indicates that the fluid exists in a single phase. At low temperatures and pressures, the properties of equilibrium vapors and liquids are extremely different e. As the pressure and temperature are increased along the coexistence curves, liquid density, viscosity, and other properties generally decrease while vapor density and viscosity generally increase.

## Specific gravity

Thus, the difference in the physical properties of the coexisting phases decreases. These changes continue as the temperature and pressure are raised until a point is reached at which the properties of the equilibrium vapor and liquid become equal.

The temperature, pressure, and volume at this point are called the "critical" values for that species. Location C on Fig.

The critical temperature and pressure are unique values for each species and are useful in correlating physical properties.

### Specific weight - Wikipedia

Critical constants for some of the commonly occurring hydrocarbons and other components of natural gas can be found in Table 1. Table 1 - Some physical constants of hydrocarbons. However, slightly different standards are sometimes used in different locations and in different units.

The ideal gas laws can be used to show that the specific gravity ratio of densities is also equal to the ratio of the molecular weights. For a fixed amount of an ideal gas kept at a fixed temperature, P [pressure] and V [volume] are inversely proportional while one increases, the other decreases. As pre…ssure increases and the density increases, the relationship becomes a bit more complex.

Increasing pressure will still decrease the volume but it becomes less proportional. If you are at a temperature below the critical point, at some point the pressure will become high enough to cause condensation of a gas to a liquid, or if you are cold enough, the precipitation of the gas as a solid the reverse of sublimation.

In these cases the relationship between pressure and volume has a discontinuity as the phase change occurs at constant pressure. What is the relationship between temperature and pressure?

The relation between temperature and pressure is known as Gay-Lussac's law, one of the gas laws. It states that the pressure exerted on a container's sides by an ideal gas is …proportional to the absolute temperature of the gas. What is the relationship between volume and weight? The relation between weight and volume -: When the weight of a substance increases, its volume also increases.

Two substances may have the same weight but different volum…es. If you have one stack of cotton and iron each of the same weight, they will have different volumes. What is the relationships between force and pressure? Archimedes a Greek mathematician who lived in third century, dicovered how to determine buoyant force.

Archimedes' principle states that the buoyant force on an object in a… fluid is an upward force equal to the weight of the volume of fluid that the object displaces.

Buoyant force is the upward force that keeps an object immersed in or floating on a liquid. What is the relationship between pressure and wind?

• Gas properties
• Fluid Density Properties

Air generally moves toward an area of low pressure. However, due to the rotation of the earth it gets deflected in large scale weather patterns.