DENSITY
*Density is the mass per unit volume of a fluid. In other words, it is the ratio between mass (m) and volume (V) of a fluid.
*Density is denoted by the symbol ‘ρ’. Its unit is kg/m3.
*In general, density of a fluid decreases with increase in temperature. It increases with increase in pressure.
SPECIFIC VOLUME
*Specific volume is the volume of a fluid (V) occupied per unit mass (m). It is the reciprocal of density.
*Specific volume is denoted by the symbol ‘v’. Its unit is m3/kg.
SPECIFIC WEIGHT
*Specific weight is the weight possessed by unit volume of a fluid. It is denoted by ‘w’. Its unit is N/m3.
*Specific weight varies from place to place due to the change of acceleration due to gravity (g
SPECIFIC GRAVITY
Specific gravity is the ratio of specific weight of the given fluid to the specific weight of standard fluid. It is denoted by the letter ‘S’. It has no unit.
VISCOSITY
*Viscosity is the fluid property that determines the amount of resistance of the fluid to shear stress. *It is the property of the fluid due to which the fluid offers resistance to flow of one layer of the fluid over another adjacent layer.
*In a liquid, viscosity decreases with increase in temperature. In a gas, viscosity increases with increase in temperature.
KINEMATIC VISCOSITY
*Kinematic viscosity is the ratio of - absolute (or dynamic) viscosity to density - a quantity in which no force is involved. Kinematic viscosity can be obtained by dividing the absolute viscosity of a fluid with the fluid mass density.
ν = μ / ρ
TEMPERATURE
*It is the property that determines the degree of hotness (or) coldness (or) the level of heat intensity of a fluid. Temperature is measured by using temperature scales.There are 3 commonly used temperature scales. They are
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Celsius (or centigrade) scale
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Fahrenheit scale
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Kelvin scale (or absolute temperature scale)
*Kelvin scale is widely used in engineering. This is because, this scale is independent of properties of a substance.
PRESSURE
*Pressure of a fluid is the force per unit area of the fluid. In other words, it is the ratio of force on a fluid to the area of the fluid held perpendicular to the direction of the force.
*Pressure is denoted by the letter ‘P’. Its unit is N/m2.
GAUGE PRESSURE
*Gauge pressure is measured with reference to atmospheric pressure and absolute pressure is measured with reference complete vaccum.
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Absolute Pressure = Atmospheric Pressure + Gauge Pressure
COMPRESSIBILITY
*Compressibility is the reciprocal of the bulk modulus of elasticity, K which is defined as the ratio of compressive stress to volumetric strain.
Compressibility = 1/K
SURFACE TENSION
Surface Tension it is defined as the cohesive forces between liquid molecules are responsible for the phenomenon known as surface tension. The molecules at the surface do not have other like molecules on all sides of them and consequently they cohere more strongly to those directly associated with them on the surface.
BUOYANCY FORCE
Buoyant force is the resultant force exerted on a body by a static fluid in which it is submerged (or) floating. Buoyant force acts through the centroid of the displaced volume of fluid, known as centre of buoyancy. This holds good for both submerged and floating bodies.
