Properties of Water and Air
Property Symbol Definition Water (20 °C) Air (STP)
Density ρ mass/volume 1000 kg/m3 1.23 kg/m>3
Viscosity μ shear stress
velocity gradient
10-3 N-s/m2 2.0×10-5 N-s/m2
Kinematic Viscosity ν viscosity/density 10-6 m2/s 1.6×10-5 m2/s
Speed of Sound c velocity of a
small wave
1480 m/s 343 m/s
Specific Weight γ weight/volume 9800 N/m3 12 N/m3
Surface Tension σ stored energy
unit area
0.073 J/m2  
Bulk Modulus K volume (ΔP/ΔV) 220×104 kPa  
Vapor Pressure pv pressure of liquid-vapor equilibrium 2.45 kPa