FLUIDS AND THEIR PROPERTIES

 

FLUIDS

Fluids are substances that flow easily and take the shape of their container. They include liquids and gases.

Examples of fluids:

• Water
• Oil
• Honey
• Molten metal
• Air
• Helium

Properties of fluids:

• Fluids are incompressible. This means that they cannot be compressed to a smaller volume without a significant increase in pressure.
• Fluids exert pressure in all directions. This is known as Pascal’s law.
• Fluids flow from areas of high pressure to areas of low pressure. This is known as Bernoulli’s principle.

Applications of fluids:

• Fluids are used in a wide variety of applications, including:
• Transportation (cars, airplanes, boats)
• Heating and cooling (radiators, air conditioners)
• Hydraulic systems (lifts, brakes)
• Lubrication (oil, grease)
• Medicine (blood, IV fluids)

Fluids in nature:

• Fluids are found all around us in nature. Some examples include:
• Water in the oceans, rivers, and lakes
• Air in the atmosphere
• Lava from volcanoes
• Blood in our bodies

 

 Fluids have several important properties, including:

• Density: Density is the mass of a fluid per unit volume. It is typically measured in kilograms per cubic meter (kg/m³). The density of a fluid is affected by its temperature and pressure. As temperature increases, density decreases. As pressure increases, density increases.
• Viscosity: Viscosity is the resistance of a fluid to flow. It is typically measured in pascal-seconds (Pa·s). The viscosity of a fluid is affected by its temperature and composition. As temperature increases, viscosity decreases. As the concentration of solute in a liquid increases, viscosity increases.
• Surface tension: Surface tension is the force that causes the surface of a fluid to contract. It is typically measured in newton’s per meter (N/m). The surface tension of a fluid is affected by its temperature and composition. As temperature increases, surface tension decreases. As the concentration of solute in a liquid increases, surface tension increases.
• Compressibility: Compressibility is the ability of a fluid to be compressed. It is typically measured in cubic meters per kilogram (m³/kg). The compressibility of a fluid is affected by its temperature and pressure. As temperature increases, compressibility increases. As pressure increases, compressibility decreases.

Examples of Fluid Properties

• Density: The density of water is 1,000 kg/m³ at room temperature and pressure. The density of air is 1.29 kg/m³ at room temperature and pressure.
• Viscosity: The viscosity of water is 0.001 Pa·s at room temperature. The viscosity of honey is 10 Pa·s at room temperature.
• Surface tension: The surface tension of water is 72.8 N/m at room temperature. The surface tension of oil is 30 N/m at room temperature.
• Compressibility: The compressibility of water is 4.5 × 10⁻¹⁰ m³/kg at room temperature and pressure. The compressibility of air is 1.0 × 10⁻⁶ m³/kg at room temperature and pressure.

·        Specific Volume

·        The specific volume of a substance is defined as the volume occupied by a unit mass of that substance. It is the reciprocal of the density of the substance. The specific volume is an intensive property, which means that it does not depend on the amount of substance present.

·        The specific volume of a substance can be expressed in various units, such as cubic meters per kilogram (m³/kg), liters per gram (L/g), or cubic feet per pound (ft³/lb). The SI unit of specific volume is cubic meters per kilogram (m³/kg).

·        Examples of Specific Volume

The following table lists the specific volumes of some common substances at room temperature and pressure:

Substance	Specific Volume (m³/kg)
Water	0.001000
Ethanol	0.001261
Gasoline	0.001350
Olive oil	0.000915
Iron	0.000071
Lead	0.000032

 

Applications of Specific Volume

The specific volume of a substance is an important property that is used in a variety of applications, such as:

• Determining the density of a substance
• Calculating the volume of a substance
• Designing and optimizing processes involving the flow of fluids
• Understanding the behavior of materials under different conditions