Properties of Fluids :-
1. Density or Mass Density
2. Specific Weight or Weight Density
3. Specific Volume
4. Specific Gravity
1. Density or Mass Density -
Density or Mass Density of a Fluid is defined as the ratio of the mass of a fluid and the Volume of Fluid. Thus mass per unit volume of a fluid is called Density.
Mass Density (ρ) = Mass of Fluid/Volume of Fluid
ρ = m/v
- It is Denoted by 'ρ' (rho).
- The SI unit of the mass Density is KG per cubic metre, kg/m³
2. Specific Weight or Weight density -
Specific Weight or weight Density of a Fluid is ratio between the weight of Fluid and its Volume called the Weight Density or the Specific weight.
Thus Mathematically -
w = Weight of Fluid/Volume of Fluid
w = (Mass of fluid) * (Accelerationdue to Gravity)/volume of fluid
= mass of fluid * g/ volume of fluid
= ρ*g ∵ (m/v = ρ)
w = ρ*g
- It is denoted by 'w' .
- The SI unit of the specific weight, N/m3
3. Specific Volume -
Specific volume of a fluid is defined as the volume of fluid occupied by a unit of mass or volume per unit mass of a fluid is called Specific volume.
Mathematically,
Specific Volume = Volume of fluid/mass of fluid
= 1/mass of fluid/volume of fluid
= 1/ρ
- It is denoted by 'v' .
- The SI unit of Specific Volume 'm 3 /kg or m 3 · kg -1 '
4. Specific Gravity -
Specific Gravity is defined as the ratio of the weight density (or density) of a fluid to the weight density of a standard fluid. For liquids, the standard fluid is taken water and for gases, the standard fluid is taken Air. Specific Gravity also called relative density.
Mathematically,
S(For liquids) = Weight density of liquids/weight densityof water
S(for Gases) = weight density of gas/weight density of Air
Thus weight density of a liquid = S*weight density of water
= S*1000*9.81 N/m3
The density of a liquid = S*density of water
= S*1000kg/m3
- The SI unit of Specific Gravity, kg m-3
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